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openssh-8.0p1-gssapi-keyex.patch
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File openssh-8.0p1-gssapi-keyex.patch of Package openssh
diff --git a/Makefile.in b/Makefile.in index e7549470..b68c1710 100644 --- a/Makefile.in +++ b/Makefile.in @@ -109,6 +109,7 @@ LIBSSH_OBJS=${LIBOPENSSH_OBJS} \ kex.o kex-names.o kexdh.o kexgex.o kexecdh.o kexc25519.o \ kexgexc.o kexgexs.o \ kexsntrup761x25519.o kexmlkem768x25519.o sntrup761.o kexgen.o \ + kexgssc.o \ sftp-realpath.o platform-pledge.o platform-tracing.o platform-misc.o \ sshbuf-io.o @@ -125,7 +126,7 @@ SSHDOBJS=sshd.o auth-rhosts.o auth-passwd.o \ auth2-chall.o groupaccess.o \ auth-bsdauth.o auth2-hostbased.o auth2-kbdint.o \ auth2-none.o auth2-passwd.o auth2-pubkey.o auth2-pubkeyfile.o \ - monitor.o monitor_wrap.o auth-krb5.o \ + monitor.o monitor_wrap.o auth-krb5.o kexgsss.o \ auth2-gss.o gss-serv.o gss-serv-krb5.o \ loginrec.o auth-pam.o auth-shadow.o auth-sia.o \ sftp-server.o sftp-common.o \ @@ -523,7 +523,7 @@ regress-prep: ln -s `cd $(srcdir) && pwd`/regress/Makefile `pwd`/regress/Makefile REGRESSLIBS=libssh.a $(LIBCOMPAT) -TESTLIBS=$(LIBS) $(CHANNELLIBS) +TESTLIBS=$(LIBS) $(CHANNELLIBS) $(GSSLIBS) regress/modpipe$(EXEEXT): $(srcdir)/regress/modpipe.c $(REGRESSLIBS) $(CC) $(CFLAGS) $(CPPFLAGS) -o $@ $(srcdir)/regress/modpipe.c \ diff -up a/auth.c.gsskex b/auth.c --- a/auth.c.gsskex 2021-08-20 06:03:49.000000000 +0200 +++ b/auth.c 2021-08-27 12:41:51.262788953 +0200 @@ -402,7 +402,8 @@ auth_root_allowed(struct ssh *ssh, const case PERMIT_NO_PASSWD: if (strcmp(method, "publickey") == 0 || strcmp(method, "hostbased") == 0 || - strcmp(method, "gssapi-with-mic") == 0) + strcmp(method, "gssapi-with-mic") == 0 || + strcmp(method, "gssapi-keyex") == 0) return 1; break; case PERMIT_FORCED_ONLY: diff --git a/auth2-gss.c b/auth2-gss.c index 9351e042..d6446c0c 100644 --- a/auth2-gss.c +++ b/auth2-gss.c @@ -54,6 +54,48 @@ static int input_gssapi_mic(int type, u_int32_t plen, struct ssh *ssh); static int input_gssapi_exchange_complete(int type, u_int32_t plen, struct ssh *ssh); static int input_gssapi_errtok(int, u_int32_t, struct ssh *); +/* + * The 'gssapi_keyex' userauth mechanism. + */ +static int +userauth_gsskeyex(struct ssh *ssh, const char *method) +{ + Authctxt *authctxt = ssh->authctxt; + int r, authenticated = 0; + struct sshbuf *b = NULL; + gss_buffer_desc mic, gssbuf; + u_char *p; + size_t len; + + if ((r = sshpkt_get_string(ssh, &p, &len)) != 0 || + (r = sshpkt_get_end(ssh)) != 0) + fatal_fr(r, "parsing"); + + if ((b = sshbuf_new()) == NULL) + fatal_f("sshbuf_new failed"); + + mic.value = p; + mic.length = len; + + ssh_gssapi_buildmic(b, authctxt->user, authctxt->service, + "gssapi-keyex", ssh->kex->session_id); + + if ((gssbuf.value = sshbuf_mutable_ptr(b)) == NULL) + fatal_f("sshbuf_mutable_ptr failed"); + gssbuf.length = sshbuf_len(b); + + /* gss_kex_context is NULL with privsep, so we can't check it here */ + if (!GSS_ERROR(mm_ssh_gssapi_checkmic(gss_kex_context, + &gssbuf, &mic))) + authenticated = mm_ssh_gssapi_userok(authctxt->user, + authctxt->pw, 1); + + sshbuf_free(b); + free(mic.value); + + return (authenticated); +} + /* * We only support those mechanisms that we know about (ie ones that we know * how to check local user kuserok and the like) @@ -260,7 +302,7 @@ input_gssapi_exchange_complete(int type, u_int32_t plen, struct ssh *ssh) if ((r = sshpkt_get_end(ssh)) != 0) fatal_fr(r, "parse packet"); - authenticated = mm_ssh_gssapi_userok(authctxt->user); + authenticated = mm_ssh_gssapi_userok(authctxt->user, authctxt->pw, 1); authctxt->postponed = 0; ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_GSSAPI_TOKEN, NULL); @@ -306,7 +349,7 @@ input_gssapi_mic(int type, u_int32_t plen, struct ssh *ssh) gssbuf.length = sshbuf_len(b); if (!GSS_ERROR(mm_ssh_gssapi_checkmic(gssctxt, &gssbuf, &mic))) - authenticated = mm_ssh_gssapi_userok(authctxt->user); + authenticated = mm_ssh_gssapi_userok(authctxt->user, authctxt->pw, 0); else logit("GSSAPI MIC check failed"); @@ -326,6 +370,17 @@ input_gssapi_mic(int type, u_int32_t plen, struct ssh *ssh) return 0; } +struct authmethod_cfg methodcfg_gsskeyex = { + "gssapi-keyex", + NULL, + &options.gss_authentication +}; + +Authmethod method_gsskeyex = { + &methodcfg_gsskeyex, + userauth_gsskeyex, +}; + Authmethod method_gssapi = { &methodcfg_gssapi, userauth_gssapi, diff --git a/auth2.c b/auth2.c index 0e776224..1c217268 100644 --- a/auth2.c +++ b/auth2.c @@ -73,6 +73,7 @@ extern Authmethod method_passwd; extern Authmethod method_kbdint; extern Authmethod method_hostbased; #ifdef GSSAPI +extern Authmethod method_gsskeyex; extern Authmethod method_gssapi; #endif @@ -80,6 +81,7 @@ Authmethod *authmethods[] = { &method_none, &method_pubkey, #ifdef GSSAPI + &method_gsskeyex, &method_gssapi, #endif &method_passwd, diff --git a/canohost.c b/canohost.c index abea9c6e..8e81b519 100644 --- a/canohost.c +++ b/canohost.c @@ -35,6 +35,99 @@ #include "canohost.h" #include "misc.h" +/* + * Returns the remote DNS hostname as a string. The returned string must not + * be freed. NB. this will usually trigger a DNS query the first time it is + * called. + * This function does additional checks on the hostname to mitigate some + * attacks on legacy rhosts-style authentication. + * XXX is RhostsRSAAuthentication vulnerable to these? + * XXX Can we remove these checks? (or if not, remove RhostsRSAAuthentication?) + */ + +char * +remote_hostname(struct ssh *ssh) +{ + struct sockaddr_storage from; + socklen_t fromlen; + struct addrinfo hints, *ai, *aitop; + char name[NI_MAXHOST], ntop2[NI_MAXHOST]; + const char *ntop = ssh_remote_ipaddr(ssh); + + /* Get IP address of client. */ + fromlen = sizeof(from); + memset(&from, 0, sizeof(from)); + if (getpeername(ssh_packet_get_connection_in(ssh), + (struct sockaddr *)&from, &fromlen) == -1) { + debug("getpeername failed: %.100s", strerror(errno)); + return xstrdup(ntop); + } + + ipv64_normalise_mapped(&from, &fromlen); + if (from.ss_family == AF_INET6) + fromlen = sizeof(struct sockaddr_in6); + + debug3("Trying to reverse map address %.100s.", ntop); + /* Map the IP address to a host name. */ + if (getnameinfo((struct sockaddr *)&from, fromlen, name, sizeof(name), + NULL, 0, NI_NAMEREQD) != 0) { + /* Host name not found. Use ip address. */ + return xstrdup(ntop); + } + + /* + * if reverse lookup result looks like a numeric hostname, + * someone is trying to trick us by PTR record like following: + * 1.1.1.10.in-addr.arpa. IN PTR 2.3.4.5 + */ + memset(&hints, 0, sizeof(hints)); + hints.ai_socktype = SOCK_DGRAM; /*dummy*/ + hints.ai_flags = AI_NUMERICHOST; + if (getaddrinfo(name, NULL, &hints, &ai) == 0) { + logit("Nasty PTR record \"%s\" is set up for %s, ignoring", + name, ntop); + freeaddrinfo(ai); + return xstrdup(ntop); + } + + /* Names are stored in lowercase. */ + lowercase(name); + + /* + * Map it back to an IP address and check that the given + * address actually is an address of this host. This is + * necessary because anyone with access to a name server can + * define arbitrary names for an IP address. Mapping from + * name to IP address can be trusted better (but can still be + * fooled if the intruder has access to the name server of + * the domain). + */ + memset(&hints, 0, sizeof(hints)); + hints.ai_family = from.ss_family; + hints.ai_socktype = SOCK_STREAM; + if (getaddrinfo(name, NULL, &hints, &aitop) != 0) { + logit("reverse mapping checking getaddrinfo for %.700s " + "[%s] failed.", name, ntop); + return xstrdup(ntop); + } + /* Look for the address from the list of addresses. */ + for (ai = aitop; ai; ai = ai->ai_next) { + if (getnameinfo(ai->ai_addr, ai->ai_addrlen, ntop2, + sizeof(ntop2), NULL, 0, NI_NUMERICHOST) == 0 && + (strcmp(ntop, ntop2) == 0)) + break; + } + freeaddrinfo(aitop); + /* If we reached the end of the list, the address was not there. */ + if (ai == NULL) { + /* Address not found for the host name. */ + logit("Address %.100s maps to %.600s, but this does not " + "map back to the address.", ntop, name); + return xstrdup(ntop); + } + return xstrdup(name); +} + void ipv64_normalise_mapped(struct sockaddr_storage *addr, socklen_t *len) { diff --git a/canohost.h b/canohost.h index 26d62855..0cadc9f1 100644 --- a/canohost.h +++ b/canohost.h @@ -15,6 +15,9 @@ #ifndef _CANOHOST_H #define _CANOHOST_H +struct ssh; + +char *remote_hostname(struct ssh *); char *get_peer_ipaddr(int); int get_peer_port(int); char *get_local_ipaddr(int); diff --git a/clientloop.c b/clientloop.c index ebd0dbca..1bdac6a4 100644 --- a/clientloop.c +++ b/clientloop.c @@ -112,6 +112,10 @@ #include "ssherr.h" #include "hostfile.h" +#ifdef GSSAPI +#include "ssh-gss.h" +#endif + /* Permitted RSA signature algorithms for UpdateHostkeys proofs */ #define HOSTKEY_PROOF_RSA_ALGS "rsa-sha2-512,rsa-sha2-256" @@ -1379,6 +1383,14 @@ client_loop(struct ssh *ssh, int have_pty, int escape_char_arg, /* Do channel operations. */ channel_after_poll(ssh, pfd, npfd_active); +#ifdef GSSAPI + if (options.gss_renewal_rekey && + ssh_gssapi_credentials_updated(NULL)) { + debug("credentials updated - forcing rekey"); + need_rekeying = 1; + } +#endif + /* Buffer input from the connection. */ if (conn_in_ready) client_process_net_input(ssh); diff --git a/configure.ac b/configure.ac index b689db4b..efafb6bd 100644 --- a/configure.ac +++ b/configure.ac @@ -674,6 +674,30 @@ main() { if (NSVersionOfRunTimeLibrary("System") >= (60 << 16)) [Use tunnel device compatibility to OpenBSD]) AC_DEFINE([SSH_TUN_PREPEND_AF], [1], [Prepend the address family to IP tunnel traffic]) + AC_MSG_CHECKING([if we have the Security Authorization Session API]) + AC_TRY_COMPILE([#include <Security/AuthSession.h>], + [SessionCreate(0, 0);], + [ac_cv_use_security_session_api="yes" + AC_DEFINE([USE_SECURITY_SESSION_API], [1], + [platform has the Security Authorization Session API]) + LIBS="$LIBS -framework Security" + AC_MSG_RESULT([yes])], + [ac_cv_use_security_session_api="no" + AC_MSG_RESULT([no])]) + AC_MSG_CHECKING([if we have an in-memory credentials cache]) + AC_TRY_COMPILE( + [#include <Kerberos/Kerberos.h>], + [cc_context_t c; + (void) cc_initialize (&c, 0, NULL, NULL);], + [AC_DEFINE([USE_CCAPI], [1], + [platform uses an in-memory credentials cache]) + LIBS="$LIBS -framework Security" + AC_MSG_RESULT([yes]) + if test "x$ac_cv_use_security_session_api" = "xno"; then + AC_MSG_ERROR([*** Need a security framework to use the credentials cache API ***]) + fi], + [AC_MSG_RESULT([no])] + ) m4_pattern_allow([AU_IPv]) AC_CHECK_DECL([AU_IPv4], [], AC_DEFINE([AU_IPv4], [0], [System only supports IPv4 audit records]) diff --git a/gss-genr.c b/gss-genr.c index d56257b4..763a63ff 100644 --- a/gss-genr.c +++ b/gss-genr.c @@ -41,9 +41,33 @@ #include "sshbuf.h" #include "log.h" #include "ssh2.h" +#include "cipher.h" +#include "sshkey.h" +#include "kex.h" +#include "digest.h" +#include "packet.h" #include "ssh-gss.h" +typedef struct { + char *encoded; + gss_OID oid; +} ssh_gss_kex_mapping; + +/* + * XXX - It would be nice to find a more elegant way of handling the + * XXX passing of the key exchange context to the userauth routines + */ + +Gssctxt *gss_kex_context = NULL; + +static ssh_gss_kex_mapping *gss_enc2oid = NULL; + +int +ssh_gssapi_oid_table_ok(void) { + return (gss_enc2oid != NULL); +} + /* sshbuf_get for gss_buffer_desc */ int ssh_gssapi_get_buffer_desc(struct sshbuf *b, gss_buffer_desc *g) @@ -62,6 +86,159 @@ ssh_gssapi_get_buffer_desc(struct sshbuf *b, gss_buffer_desc *g) return 0; } +/* sshpkt_get of gss_buffer_desc */ +int +ssh_gssapi_sshpkt_get_buffer_desc(struct ssh *ssh, gss_buffer_desc *g) +{ + int r; + u_char *p; + size_t len; + + if ((r = sshpkt_get_string(ssh, &p, &len)) != 0) + return r; + g->value = p; + g->length = len; + return 0; +} + +/* + * Return a list of the gss-group1-sha1 mechanisms supported by this program + * + * We test mechanisms to ensure that we can use them, to avoid starting + * a key exchange with a bad mechanism + */ + +char * +ssh_gssapi_client_mechanisms(const char *host, const char *client, + const char *kex) { + gss_OID_set gss_supported = NULL; + OM_uint32 min_status; + + if (GSS_ERROR(gss_indicate_mechs(&min_status, &gss_supported))) + return NULL; + + return ssh_gssapi_kex_mechs(gss_supported, ssh_gssapi_check_mechanism, + host, client, kex); +} + +char * +ssh_gssapi_kex_mechs(gss_OID_set gss_supported, ssh_gssapi_check_fn *check, + const char *host, const char *client, const char *kex) { + struct sshbuf *buf = NULL; + size_t i; + int r = SSH_ERR_ALLOC_FAIL; + int oidpos, enclen; + char *mechs, *encoded; + u_char digest[SSH_DIGEST_MAX_LENGTH]; + char deroid[2]; + struct ssh_digest_ctx *md = NULL; + char *s, *cp, *p; + + if (gss_enc2oid != NULL) { + for (i = 0; gss_enc2oid[i].encoded != NULL; i++) + free(gss_enc2oid[i].encoded); + free(gss_enc2oid); + } + + gss_enc2oid = xmalloc(sizeof(ssh_gss_kex_mapping) * + (gss_supported->count + 1)); + + if ((buf = sshbuf_new()) == NULL) + fatal_f("sshbuf_new failed"); + + oidpos = 0; + s = cp = xstrdup(kex); + for (i = 0; i < gss_supported->count; i++) { + if (gss_supported->elements[i].length < 128 && + (*check)(NULL, &(gss_supported->elements[i]), host, client)) { + + deroid[0] = SSH_GSS_OIDTYPE; + deroid[1] = gss_supported->elements[i].length; + + if ((md = ssh_digest_start(SSH_DIGEST_MD5)) == NULL || + (r = ssh_digest_update(md, deroid, 2)) != 0 || + (r = ssh_digest_update(md, + gss_supported->elements[i].elements, + gss_supported->elements[i].length)) != 0 || + (r = ssh_digest_final(md, digest, sizeof(digest))) != 0) + fatal_fr(r, "digest failed"); + ssh_digest_free(md); + md = NULL; + + encoded = xmalloc(ssh_digest_bytes(SSH_DIGEST_MD5) + * 2); + enclen = __b64_ntop(digest, + ssh_digest_bytes(SSH_DIGEST_MD5), encoded, + ssh_digest_bytes(SSH_DIGEST_MD5) * 2); + + cp = strncpy(s, kex, strlen(kex)); + for ((p = strsep(&cp, ",")); p && *p != '\0'; + (p = strsep(&cp, ","))) { + if (sshbuf_len(buf) != 0 && + (r = sshbuf_put_u8(buf, ',')) != 0) + fatal_fr(r, "sshbuf_put_u8 error"); + if ((r = sshbuf_put(buf, p, strlen(p))) != 0 || + (r = sshbuf_put(buf, encoded, enclen)) != 0) + fatal_fr(r, "sshbuf_put error"); + } + + gss_enc2oid[oidpos].oid = &(gss_supported->elements[i]); + gss_enc2oid[oidpos].encoded = encoded; + oidpos++; + } + } + free(s); + gss_enc2oid[oidpos].oid = NULL; + gss_enc2oid[oidpos].encoded = NULL; + + if ((mechs = sshbuf_dup_string(buf)) == NULL) + fatal_f("sshbuf_dup_string failed"); + + sshbuf_free(buf); + + if (strlen(mechs) == 0) { + free(mechs); + mechs = NULL; + } + + return (mechs); +} + +gss_OID +ssh_gssapi_id_kex(Gssctxt *ctx, char *name, int kex_type) { + int i = 0; + +#define SKIP_KEX_NAME(type) \ + case type: \ + if (strlen(name) < sizeof(type##_ID)) \ + return GSS_C_NO_OID; \ + name += sizeof(type##_ID) - 1; \ + break; + + switch (kex_type) { + SKIP_KEX_NAME(KEX_GSS_GRP1_SHA1) + SKIP_KEX_NAME(KEX_GSS_GRP14_SHA1) + SKIP_KEX_NAME(KEX_GSS_GRP14_SHA256) + SKIP_KEX_NAME(KEX_GSS_GRP16_SHA512) + SKIP_KEX_NAME(KEX_GSS_GEX_SHA1) + SKIP_KEX_NAME(KEX_GSS_NISTP256_SHA256) + SKIP_KEX_NAME(KEX_GSS_C25519_SHA256) + default: + return GSS_C_NO_OID; + } + +#undef SKIP_KEX_NAME + + while (gss_enc2oid[i].encoded != NULL && + strcmp(name, gss_enc2oid[i].encoded) != 0) + i++; + + if (gss_enc2oid[i].oid != NULL && ctx != NULL) + ssh_gssapi_set_oid(ctx, gss_enc2oid[i].oid); + + return gss_enc2oid[i].oid; +} + /* Check that the OID in a data stream matches that in the context */ int ssh_gssapi_check_oid(Gssctxt *ctx, void *data, size_t len) @@ -218,7 +398,7 @@ ssh_gssapi_init_ctx(Gssctxt *ctx, int deleg_creds, gss_buffer_desc *recv_tok, } ctx->major = gss_init_sec_context(&ctx->minor, - GSS_C_NO_CREDENTIAL, &ctx->context, ctx->name, ctx->oid, + ctx->client_creds, &ctx->context, ctx->name, ctx->oid, GSS_C_MUTUAL_FLAG | GSS_C_INTEG_FLAG | deleg_flag, 0, NULL, recv_tok, NULL, send_tok, flags, NULL); @@ -247,9 +427,43 @@ ssh_gssapi_import_name(Gssctxt *ctx, const char *host) return (ctx->major); } +OM_uint32 +ssh_gssapi_client_identity(Gssctxt *ctx, const char *name) +{ + gss_buffer_desc gssbuf; + gss_name_t gssname; + OM_uint32 status; + gss_OID_set oidset; + + gssbuf.value = (void *) name; + gssbuf.length = strlen(gssbuf.value); + + gss_create_empty_oid_set(&status, &oidset); + gss_add_oid_set_member(&status, ctx->oid, &oidset); + + ctx->major = gss_import_name(&ctx->minor, &gssbuf, + GSS_C_NT_USER_NAME, &gssname); + + if (!ctx->major) + ctx->major = gss_acquire_cred(&ctx->minor, + gssname, 0, oidset, GSS_C_INITIATE, + &ctx->client_creds, NULL, NULL); + + gss_release_name(&status, &gssname); + gss_release_oid_set(&status, &oidset); + + if (ctx->major) + ssh_gssapi_error(ctx); + + return(ctx->major); +} + OM_uint32 ssh_gssapi_sign(Gssctxt *ctx, gss_buffer_t buffer, gss_buffer_t hash) { + if (ctx == NULL) + return -1; + if ((ctx->major = gss_get_mic(&ctx->minor, ctx->context, GSS_C_QOP_DEFAULT, buffer, hash))) ssh_gssapi_error(ctx); @@ -257,6 +471,19 @@ ssh_gssapi_sign(Gssctxt *ctx, gss_buffer_t buffer, gss_buffer_t hash) return (ctx->major); } +/* Priviledged when used by server */ +OM_uint32 +ssh_gssapi_checkmic(Gssctxt *ctx, gss_buffer_t gssbuf, gss_buffer_t gssmic) +{ + if (ctx == NULL) + return -1; + + ctx->major = gss_verify_mic(&ctx->minor, ctx->context, + gssbuf, gssmic, NULL); + + return (ctx->major); +} + void ssh_gssapi_buildmic(struct sshbuf *b, const char *user, const char *service, const char *context, const struct sshbuf *session_id) @@ -273,11 +500,16 @@ ssh_gssapi_buildmic(struct sshbuf *b, const char *user, const char *service, } int -ssh_gssapi_check_mechanism(Gssctxt **ctx, gss_OID oid, const char *host) +ssh_gssapi_check_mechanism(Gssctxt **ctx, gss_OID oid, const char *host, + const char *client) { gss_buffer_desc token = GSS_C_EMPTY_BUFFER; OM_uint32 major, minor; gss_OID_desc spnego_oid = {6, (void *)"\x2B\x06\x01\x05\x05\x02"}; + Gssctxt *intctx = NULL; + + if (ctx == NULL) + ctx = &intctx; /* RFC 4462 says we MUST NOT do SPNEGO */ if (oid->length == spnego_oid.length && @@ -500,6 +500,10 @@ ssh_gssapi_check_mechanism(Gssctxt **ctx, gss_OID oid, const char *host) ssh_gssapi_build_ctx(ctx); ssh_gssapi_set_oid(*ctx, oid); major = ssh_gssapi_import_name(*ctx, host); + + if (!GSS_ERROR(major) && client) + major = ssh_gssapi_client_identity(*ctx, client); + if (!GSS_ERROR(major)) { major = ssh_gssapi_init_ctx(*ctx, 0, GSS_C_NO_BUFFER, &token, NULL); @@ -527,10 +527,66 @@ ssh_gssapi_check_mechanism(Gssctxt **ctx GSS_C_NO_BUFFER); } - if (GSS_ERROR(major)) + if (GSS_ERROR(major) || intctx != NULL) ssh_gssapi_delete_ctx(ctx); return (!GSS_ERROR(major)); } +int +ssh_gssapi_credentials_updated(Gssctxt *ctxt) { + static gss_name_t saved_name = GSS_C_NO_NAME; + static OM_uint32 saved_lifetime = 0; + static gss_OID saved_mech = GSS_C_NO_OID; + static gss_name_t name; + static OM_uint32 last_call = 0; + OM_uint32 lifetime, now, major, minor; + int equal; + + now = time(NULL); + + if (ctxt) { + debug("Rekey has happened - updating saved versions"); + + if (saved_name != GSS_C_NO_NAME) + gss_release_name(&minor, &saved_name); + + major = gss_inquire_cred(&minor, GSS_C_NO_CREDENTIAL, + &saved_name, &saved_lifetime, NULL, NULL); + + if (!GSS_ERROR(major)) { + saved_mech = ctxt->oid; + saved_lifetime+= now; + } else { + /* Handle the error */ + } + return 0; + } + + if (now - last_call < 10) + return 0; + + last_call = now; + + if (saved_mech == GSS_C_NO_OID) + return 0; + + major = gss_inquire_cred(&minor, GSS_C_NO_CREDENTIAL, + &name, &lifetime, NULL, NULL); + if (major == GSS_S_CREDENTIALS_EXPIRED) + return 0; + else if (GSS_ERROR(major)) + return 0; + + major = gss_compare_name(&minor, saved_name, name, &equal); + gss_release_name(&minor, &name); + if (GSS_ERROR(major)) + return 0; + + if (equal && (saved_lifetime < lifetime + now - 10)) + return 1; + + return 0; +} + #endif /* GSSAPI */ diff --git a/gss-serv-krb5.c b/gss-serv-krb5.c index a151bc1e..8d2b677f 100644 --- a/gss-serv-krb5.c +++ b/gss-serv-krb5.c @@ -1,7 +1,7 @@ /* $OpenBSD: gss-serv-krb5.c,v 1.9 2018/07/09 21:37:55 markus Exp $ */ /* - * Copyright (c) 2001-2003 Simon Wilkinson. All rights reserved. + * Copyright (c) 2001-2007 Simon Wilkinson. All rights reserved. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions @@ -120,7 +120,7 @@ ssh_gssapi_krb5_storecreds(ssh_gssapi_client *client) krb5_error_code problem; krb5_principal princ; OM_uint32 maj_status, min_status; - int len; + const char *new_ccname, *new_cctype; const char *errmsg; if (client->creds == NULL) { @@ -180,11 +180,26 @@ ssh_gssapi_krb5_storecreds(ssh_gssapi_client *client) return; } - client->store.filename = xstrdup(krb5_cc_get_name(krb_context, ccache)); + new_cctype = krb5_cc_get_type(krb_context, ccache); + new_ccname = krb5_cc_get_name(krb_context, ccache); + client->store.envvar = "KRB5CCNAME"; - len = strlen(client->store.filename) + 6; - client->store.envval = xmalloc(len); - snprintf(client->store.envval, len, "FILE:%s", client->store.filename); +#ifdef USE_CCAPI + xasprintf(&client->store.envval, "API:%s", new_ccname); + client->store.filename = NULL; +#else + if (new_ccname[0] == ':') + new_ccname++; + xasprintf(&client->store.envval, "%s:%s", new_cctype, new_ccname); + if (strcmp(new_cctype, "DIR") == 0) { + char *p; + p = strrchr(client->store.envval, '/'); + if (p) + *p = '\0'; + } + if ((strcmp(new_cctype, "FILE") == 0) || (strcmp(new_cctype, "DIR") == 0)) + client->store.filename = xstrdup(new_ccname); +#endif #ifdef USE_PAM if (options.use_pam) @@ -193,9 +208,76 @@ ssh_gssapi_krb5_storecreds(ssh_gssapi_client *client) krb5_cc_close(krb_context, ccache); + client->store.data = krb_context; + return; } +int +ssh_gssapi_krb5_updatecreds(ssh_gssapi_ccache *store, + ssh_gssapi_client *client) +{ + krb5_ccache ccache = NULL; + krb5_principal principal = NULL; + char *name = NULL; + krb5_error_code problem; + OM_uint32 maj_status, min_status; + + if ((problem = krb5_cc_resolve(krb_context, store->envval, &ccache))) { + logit("krb5_cc_resolve(): %.100s", + krb5_get_err_text(krb_context, problem)); + return 0; + } + + /* Find out who the principal in this cache is */ + if ((problem = krb5_cc_get_principal(krb_context, ccache, + &principal))) { + logit("krb5_cc_get_principal(): %.100s", + krb5_get_err_text(krb_context, problem)); + krb5_cc_close(krb_context, ccache); + return 0; + } + + if ((problem = krb5_unparse_name(krb_context, principal, &name))) { + logit("krb5_unparse_name(): %.100s", + krb5_get_err_text(krb_context, problem)); + krb5_free_principal(krb_context, principal); + krb5_cc_close(krb_context, ccache); + return 0; + } + + + if (strcmp(name,client->exportedname.value)!=0) { + debug("Name in local credentials cache differs. Not storing"); + krb5_free_principal(krb_context, principal); + krb5_cc_close(krb_context, ccache); + krb5_free_unparsed_name(krb_context, name); + return 0; + } + krb5_free_unparsed_name(krb_context, name); + + /* Name matches, so lets get on with it! */ + + if ((problem = krb5_cc_initialize(krb_context, ccache, principal))) { + logit("krb5_cc_initialize(): %.100s", + krb5_get_err_text(krb_context, problem)); + krb5_free_principal(krb_context, principal); + krb5_cc_close(krb_context, ccache); + return 0; + } + + krb5_free_principal(krb_context, principal); + + if ((maj_status = gss_krb5_copy_ccache(&min_status, client->creds, + ccache))) { + logit("gss_krb5_copy_ccache() failed. Sorry!"); + krb5_cc_close(krb_context, ccache); + return 0; + } + + return 1; +} + ssh_gssapi_mech gssapi_kerberos_mech = { "toWM5Slw5Ew8Mqkay+al2g==", "Kerberos", @@ -203,7 +285,8 @@ ssh_gssapi_mech gssapi_kerberos_mech = { NULL, &ssh_gssapi_krb5_userok, NULL, - &ssh_gssapi_krb5_storecreds + &ssh_gssapi_krb5_storecreds, + &ssh_gssapi_krb5_updatecreds }; #endif /* KRB5 */ diff --git a/gss-serv.c b/gss-serv.c index ab3a15f0..6ce56e92 100644 --- a/gss-serv.c +++ b/gss-serv.c @@ -1,7 +1,7 @@ /* $OpenBSD: gss-serv.c,v 1.32 2020/03/13 03:17:07 djm Exp $ */ /* - * Copyright (c) 2001-2003 Simon Wilkinson. All rights reserved. + * Copyright (c) 2001-2009 Simon Wilkinson. All rights reserved. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions @@ -44,17 +44,19 @@ #include "session.h" #include "misc.h" #include "servconf.h" +#include "uidswap.h" #include "ssh-gss.h" +#include "monitor_wrap.h" extern ServerOptions options; static ssh_gssapi_client gssapi_client = - { GSS_C_EMPTY_BUFFER, GSS_C_EMPTY_BUFFER, - GSS_C_NO_CREDENTIAL, NULL, {NULL, NULL, NULL, NULL}}; + { GSS_C_EMPTY_BUFFER, GSS_C_EMPTY_BUFFER, GSS_C_NO_CREDENTIAL, + GSS_C_NO_NAME, NULL, {NULL, NULL, NULL, NULL, NULL}, 0, 0}; ssh_gssapi_mech gssapi_null_mech = - { NULL, NULL, {0, NULL}, NULL, NULL, NULL, NULL}; + { NULL, NULL, {0, NULL}, NULL, NULL, NULL, NULL, NULL}; #ifdef KRB5 extern ssh_gssapi_mech gssapi_kerberos_mech; @@ -140,6 +142,29 @@ ssh_gssapi_server_ctx(Gssctxt **ctx, gss_OID oid) return (ssh_gssapi_acquire_cred(*ctx)); } +/* Unprivileged */ +char * +ssh_gssapi_server_mechanisms(void) { + if (supported_oids == NULL) + ssh_gssapi_prepare_supported_oids(); + return (ssh_gssapi_kex_mechs(supported_oids, + &ssh_gssapi_server_check_mech, NULL, NULL, + options.gss_kex_algorithms)); +} + +/* Unprivileged */ +int +ssh_gssapi_server_check_mech(Gssctxt **dum, gss_OID oid, const char *data, + const char *dummy) { + Gssctxt *ctx = NULL; + int res; + + res = !GSS_ERROR(mm_ssh_gssapi_server_ctx(&ctx, oid)); + ssh_gssapi_delete_ctx(&ctx); + + return (res); +} + /* Unprivileged */ void ssh_gssapi_supported_oids(gss_OID_set *oidset) @@ -150,7 +175,9 @@ ssh_gssapi_supported_oids(gss_OID_set *oidset) gss_OID_set supported; gss_create_empty_oid_set(&min_status, oidset); - gss_indicate_mechs(&min_status, &supported); + + if (GSS_ERROR(gss_indicate_mechs(&min_status, &supported))) + return; while (supported_mechs[i]->name != NULL) { if (GSS_ERROR(gss_test_oid_set_member(&min_status, @@ -276,8 +303,48 @@ OM_uint32 ssh_gssapi_getclient(Gssctxt *ctx, ssh_gssapi_client *client) { int i = 0; + int equal = 0; + gss_name_t new_name = GSS_C_NO_NAME; + gss_buffer_desc ename = GSS_C_EMPTY_BUFFER; + + if (options.gss_store_rekey && client->used && ctx->client_creds) { + if (client->mech->oid.length != ctx->oid->length || + (memcmp(client->mech->oid.elements, + ctx->oid->elements, ctx->oid->length) !=0)) { + debug("Rekeyed credentials have different mechanism"); + return GSS_S_COMPLETE; + } + + if ((ctx->major = gss_inquire_cred_by_mech(&ctx->minor, + ctx->client_creds, ctx->oid, &new_name, + NULL, NULL, NULL))) { + ssh_gssapi_error(ctx); + return (ctx->major); + } - gss_buffer_desc ename; + ctx->major = gss_compare_name(&ctx->minor, client->name, + new_name, &equal); + + if (GSS_ERROR(ctx->major)) { + ssh_gssapi_error(ctx); + return (ctx->major); + } + + if (!equal) { + debug("Rekeyed credentials have different name"); + return GSS_S_COMPLETE; + } + + debug("Marking rekeyed credentials for export"); + + gss_release_name(&ctx->minor, &client->name); + gss_release_cred(&ctx->minor, &client->creds); + client->name = new_name; + client->creds = ctx->client_creds; + ctx->client_creds = GSS_C_NO_CREDENTIAL; + client->updated = 1; + return GSS_S_COMPLETE; + } client->mech = NULL; @@ -292,6 +359,13 @@ ssh_gssapi_getclient(Gssctxt *ctx, ssh_gssapi_client *client) if (client->mech == NULL) return GSS_S_FAILURE; + if (ctx->client_creds && + (ctx->major = gss_inquire_cred_by_mech(&ctx->minor, + ctx->client_creds, ctx->oid, &client->name, NULL, NULL, NULL))) { + ssh_gssapi_error(ctx); + return (ctx->major); + } + if ((ctx->major = gss_display_name(&ctx->minor, ctx->client, &client->displayname, NULL))) { ssh_gssapi_error(ctx); @@ -309,6 +383,8 @@ ssh_gssapi_getclient(Gssctxt *ctx, ssh_gssapi_client *client) return (ctx->major); } + gss_release_buffer(&ctx->minor, &ename); + /* We can't copy this structure, so we just move the pointer to it */ client->creds = ctx->client_creds; ctx->client_creds = GSS_C_NO_CREDENTIAL; @@ -319,11 +395,20 @@ ssh_gssapi_getclient(Gssctxt *ctx, ssh_gssapi_client *client) void ssh_gssapi_cleanup_creds(void) { - if (gssapi_client.store.filename != NULL) { - /* Unlink probably isn't sufficient */ - debug("removing gssapi cred file\"%s\"", - gssapi_client.store.filename); - unlink(gssapi_client.store.filename); + krb5_ccache ccache = NULL; + krb5_error_code problem; + + if (gssapi_client.store.data != NULL) { + if ((problem = krb5_cc_resolve(gssapi_client.store.data, gssapi_client.store.envval, &ccache))) { + debug_f("krb5_cc_resolve(): %.100s", + krb5_get_err_text(gssapi_client.store.data, problem)); + } else if ((problem = krb5_cc_destroy(gssapi_client.store.data, ccache))) { + debug_f("krb5_cc_destroy(): %.100s", + krb5_get_err_text(gssapi_client.store.data, problem)); + } else { + krb5_free_context(gssapi_client.store.data); + gssapi_client.store.data = NULL; + } } } @@ -356,19 +441,23 @@ ssh_gssapi_do_child(char ***envp, u_int *envsizep) /* Privileged */ int -ssh_gssapi_userok(char *user) +ssh_gssapi_userok(char *user, struct passwd *pw, int kex) { OM_uint32 lmin; + (void) kex; /* used in privilege separation */ + if (gssapi_client.exportedname.length == 0 || gssapi_client.exportedname.value == NULL) { debug("No suitable client data"); return 0; } if (gssapi_client.mech && gssapi_client.mech->userok) - if ((*gssapi_client.mech->userok)(&gssapi_client, user)) + if ((*gssapi_client.mech->userok)(&gssapi_client, user)) { + gssapi_client.used = 1; + gssapi_client.store.owner = pw; return 1; - else { + } else { /* Destroy delegated credentials if userok fails */ gss_release_buffer(&lmin, &gssapi_client.displayname); gss_release_buffer(&lmin, &gssapi_client.exportedname); @@ -382,14 +471,85 @@ ssh_gssapi_userok(char *user) return (0); } -/* Privileged */ -OM_uint32 -ssh_gssapi_checkmic(Gssctxt *ctx, gss_buffer_t gssbuf, gss_buffer_t gssmic) +/* These bits are only used for rekeying. The unpriviledged child is running + * as the user, the monitor is root. + * + * In the child, we want to : + * *) Ask the monitor to store our credentials into the store we specify + * *) If it succeeds, maybe do a PAM update + */ + +/* Stuff for PAM */ + +#ifdef USE_PAM +static int ssh_gssapi_simple_conv(int n, const struct pam_message **msg, + struct pam_response **resp, void *data) { - ctx->major = gss_verify_mic(&ctx->minor, ctx->context, - gssbuf, gssmic, NULL); + return (PAM_CONV_ERR); +} +#endif - return (ctx->major); +void +ssh_gssapi_rekey_creds(void) { + int ok; +#ifdef USE_PAM + int ret; + pam_handle_t *pamh = NULL; + struct pam_conv pamconv = {ssh_gssapi_simple_conv, NULL}; + char *envstr; +#endif + + if (gssapi_client.store.filename == NULL && + gssapi_client.store.envval == NULL && + gssapi_client.store.envvar == NULL) + return; + + ok = mm_ssh_gssapi_update_creds(&gssapi_client.store); + + if (!ok) + return; + + debug("Rekeyed credentials stored successfully"); + + /* Actually managing to play with the ssh pam stack from here will + * be next to impossible. In any case, we may want different options + * for rekeying. So, use our own :) + */ +#ifdef USE_PAM + ret = pam_start("sshd-rekey", gssapi_client.store.owner->pw_name, + &pamconv, &pamh); + if (ret) + return; + + xasprintf(&envstr, "%s=%s", gssapi_client.store.envvar, + gssapi_client.store.envval); + + ret = pam_putenv(pamh, envstr); + if (!ret) + pam_setcred(pamh, PAM_REINITIALIZE_CRED); + pam_end(pamh, PAM_SUCCESS); +#endif +} + +int +ssh_gssapi_update_creds(ssh_gssapi_ccache *store) { + int ok = 0; + + /* Check we've got credentials to store */ + if (!gssapi_client.updated) + return 0; + + gssapi_client.updated = 0; + + temporarily_use_uid(gssapi_client.store.owner); + if (gssapi_client.mech && gssapi_client.mech->updatecreds) + ok = (*gssapi_client.mech->updatecreds)(store, &gssapi_client); + else + debug("No update function for this mechanism"); + + restore_uid(); + + return ok; } /* Privileged */ diff --git a/kex.c b/kex.c index a5ae6ac0..fe714141 100644 --- a/kex.c +++ b/kex.c @@ -698,6 +755,9 @@ kex_free(struct kex *kex) sshbuf_free(kex->server_version); sshbuf_free(kex->client_pub); sshbuf_free(kex->session_id); +#ifdef GSSAPI + free(kex->gss_host); +#endif /* GSSAPI */ sshbuf_free(kex->initial_sig); sshkey_free(kex->initial_hostkey); free(kex->failed_choice); diff --git a/kex-names.c b/kex-names.c index ce85f043..574c7609 100644 --- a/kex-names.c +++ b/kex-names.c @@ -57,6 +57,10 @@ #include "fips.h" +#ifdef GSSAPI +#include "ssh-gss.h" +#endif + struct kexalg { char *name; u_int type; @@ -110,6 +113,30 @@ static const struct kexalg kexalgs[] = { #endif /* WITH_OPENSSL */ { NULL, -1, -1, -1}, }; +static const struct kexalg gss_kexalgs_all[] = { +#ifdef GSSAPI + { KEX_GSS_GEX_SHA1_ID, KEX_GSS_GEX_SHA1, 0, SSH_DIGEST_SHA1 }, + { KEX_GSS_GRP1_SHA1_ID, KEX_GSS_GRP1_SHA1, 0, SSH_DIGEST_SHA1 }, + { KEX_GSS_GRP14_SHA1_ID, KEX_GSS_GRP14_SHA1, 0, SSH_DIGEST_SHA1 }, + { KEX_GSS_GRP14_SHA256_ID, KEX_GSS_GRP14_SHA256, 0, SSH_DIGEST_SHA256 }, + { KEX_GSS_GRP16_SHA512_ID, KEX_GSS_GRP16_SHA512, 0, SSH_DIGEST_SHA512 }, + { KEX_GSS_NISTP256_SHA256_ID, KEX_GSS_NISTP256_SHA256, + NID_X9_62_prime256v1, SSH_DIGEST_SHA256 }, + { KEX_GSS_C25519_SHA256_ID, KEX_GSS_C25519_SHA256, 0, SSH_DIGEST_SHA256 }, +#endif + { NULL, 0, -1, -1}, +}; + +static const struct kexalg gss_kexalgs_fips140_2[] = { +#ifdef GSSAPI + { KEX_GSS_GRP14_SHA256_ID, KEX_GSS_GRP14_SHA256, 0, SSH_DIGEST_SHA256 }, + { KEX_GSS_GRP16_SHA512_ID, KEX_GSS_GRP16_SHA512, 0, SSH_DIGEST_SHA512 }, + { KEX_GSS_NISTP256_SHA256_ID, KEX_GSS_NISTP256_SHA256, + NID_X9_62_prime256v1, SSH_DIGEST_SHA256 }, + { KEX_GSS_C25519_SHA256_ID, KEX_GSS_C25519_SHA256, 0, SSH_DIGEST_SHA256 }, +#endif + { NULL, 0, -1, -1}, +}; /* Returns array of macs available depending on selected FIPS mode */ static const struct kexalg * @@ -120,14 +140,31 @@ fips_select_kexalgs(void) } } +/* Returns array of macs available depending on selected FIPS mode */ +static const struct kexalg * +fips_select_gss_kexalgs(void) +{ + int fips = fips_mode(); + switch (fips) { + case 0: + return gss_kexalgs_all; + case 1: + return gss_kexalgs_fips140_2; + default: + /* should not be reached */ + fatal("Fatal error: incorrect FIPS mode '%i' at %s:%u", + fips, __FILE__, __LINE__); + } +} + -char * -kex_alg_list(char sep) +static char * +kex_alg_list_internal(char sep, const struct kexalg *algs) { char *ret = NULL, *tmp; size_t nlen, rlen = 0; const struct kexalg *k; - for (k = fips_select_kexalgs(); k->name != NULL; k++) { + for (k = algs; k->name != NULL; k++) { if (ret != NULL) ret[rlen++] = sep; nlen = strlen(k->name); @@ -138,6 +156,18 @@ kex_alg_list(char sep) return ret; } +char * +kex_alg_list(char sep) +{ + return kex_alg_list_internal(sep, fips_select_kexalgs()); +} + +char * +kex_gss_alg_list(char sep) +{ + return kex_alg_list_internal(sep, fips_select_gss_kexalgs()); +} + static const struct kexalg * kex_alg_by_name(const char *name) { @@ -147,6 +177,10 @@ kex_alg_by_name(const char *name) if (strcmp(k->name, name) == 0) return k; } + for (k = gss_kexalgs_all; k->name != NULL; k++) { + if (strncmp(k->name, name, strlen(k->name)) == 0) + return k; + } return NULL; } @@ -315,3 +349,26 @@ kex_assemble_names(char **listp, const char *def, const char *all) free(ret); return r; } + +/* Validate GSS KEX method name list */ +int +kex_gss_names_valid(const char *names) +{ + char *s, *cp, *p; + + if (names == NULL || *names == '\0') + return 0; + s = cp = xstrdup(names); + for ((p = strsep(&cp, ",")); p && *p != '\0'; + (p = strsep(&cp, ","))) { + if (strncmp(p, "gss-", 4) != 0 + || kex_alg_by_name(p) == NULL) { + error("Unsupported KEX algorithm \"%.100s\"", p); + free(s); + return 0; + } + } + debug3("gss kex names ok: [%s]", names); + free(s); + return 1; +} diff --git a/kex.h b/kex.h index a5ae6ac0..fe714141 100644 --- a/kex.h +++ b/kex.h @@ -102,6 +102,15 @@ enum kex_exchange { KEX_C25519_SHA256, KEX_KEM_SNTRUP761X25519_SHA512, KEX_KEM_MLKEM768X25519_SHA256, +#ifdef GSSAPI + KEX_GSS_GRP1_SHA1, + KEX_GSS_GRP14_SHA1, + KEX_GSS_GRP14_SHA256, + KEX_GSS_GRP16_SHA512, + KEX_GSS_GEX_SHA1, + KEX_GSS_NISTP256_SHA256, + KEX_GSS_C25519_SHA256, +#endif KEX_MAX }; @@ -153,6 +162,12 @@ struct kex { u_int flags; int hash_alg; int ec_nid; +#ifdef GSSAPI + int gss_deleg_creds; + int gss_trust_dns; + char *gss_host; + char *gss_client; +#endif char *failed_choice; int (*verify_host_key)(struct sshkey *, struct ssh *); struct sshkey *(*load_host_public_key)(int, int, struct ssh *); @@ -174,8 +189,10 @@ struct kex { int kex_nid_from_name(const char *); int kex_names_valid(const char *); char *kex_alg_list(char); +char *kex_gss_alg_list(char); char *kex_names_cat(const char *, const char *); int kex_has_any_alg(const char *, const char *); +int kex_gss_names_valid(const char *); int kex_assemble_names(char **, const char *, const char *); void kex_proposal_populate_entries(struct ssh *, char *prop[PROPOSAL_MAX], const char *, const char *, const char *, const char *, const char *); @@ -202,6 +219,12 @@ int kexgex_client(struct ssh *); int kexgex_server(struct ssh *); int kex_gen_client(struct ssh *); int kex_gen_server(struct ssh *); +#if defined(GSSAPI) && defined(WITH_OPENSSL) +int kexgssgex_client(struct ssh *); +int kexgssgex_server(struct ssh *); +int kexgss_client(struct ssh *); +int kexgss_server(struct ssh *); +#endif int kex_dh_keypair(struct kex *); int kex_dh_enc(struct kex *, const struct sshbuf *, struct sshbuf **, @@ -234,6 +257,12 @@ int kexgex_hash(int, const struct sshbuf *, const struct sshbuf *, const BIGNUM *, const u_char *, size_t, u_char *, size_t *); +int kex_gen_hash(int hash_alg, const struct sshbuf *client_version, + const struct sshbuf *server_version, const struct sshbuf *client_kexinit, + const struct sshbuf *server_kexinit, const struct sshbuf *server_host_key_blob, + const struct sshbuf *client_pub, const struct sshbuf *server_pub, + const struct sshbuf *shared_secret, u_char *hash, size_t *hashlen); + void kexc25519_keygen(u_char key[CURVE25519_SIZE], u_char pub[CURVE25519_SIZE]) __attribute__((__bounded__(__minbytes__, 1, CURVE25519_SIZE))) __attribute__((__bounded__(__minbytes__, 2, CURVE25519_SIZE))); diff --git a/kexdh.c b/kexdh.c index 67133e33..edaa4676 100644 --- a/kexdh.c +++ b/kexdh.c @@ -48,13 +48,23 @@ kex_dh_keygen(struct kex *kex) { switch (kex->kex_type) { case KEX_DH_GRP1_SHA1: +#ifdef GSSAPI + case KEX_GSS_GRP1_SHA1: +#endif kex->dh = dh_new_group1(); break; case KEX_DH_GRP14_SHA1: case KEX_DH_GRP14_SHA256: +#ifdef GSSAPI + case KEX_GSS_GRP14_SHA1: + case KEX_GSS_GRP14_SHA256: +#endif kex->dh = dh_new_group14(); break; case KEX_DH_GRP16_SHA512: +#ifdef GSSAPI + case KEX_GSS_GRP16_SHA512: +#endif kex->dh = dh_new_group16(); break; case KEX_DH_GRP18_SHA512: diff --git a/kexgen.c b/kexgen.c index 69348b96..c0e8c2f4 100644 --- a/kexgen.c +++ b/kexgen.c @@ -44,7 +44,7 @@ static int input_kex_gen_init(int, u_int32_t, struct ssh *); static int input_kex_gen_reply(int type, u_int32_t seq, struct ssh *ssh); -static int +int kex_gen_hash( int hash_alg, const struct sshbuf *client_version, diff --git a/kexgssc.c b/kexgssc.c new file mode 100644 index 00000000..f6e1405e --- /dev/null +++ b/kexgssc.c @@ -0,0 +1,612 @@ +/* + * Copyright (c) 2001-2009 Simon Wilkinson. All rights reserved. + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions + * are met: + * 1. Redistributions of source code must retain the above copyright + * notice, this list of conditions and the following disclaimer. + * 2. Redistributions in binary form must reproduce the above copyright + * notice, this list of conditions and the following disclaimer in the + * documentation and/or other materials provided with the distribution. + * + * THIS SOFTWARE IS PROVIDED BY THE AUTHOR `AS IS'' AND ANY EXPRESS OR + * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES + * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. + * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, + * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT + * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, + * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY + * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT + * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF + * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. + */ + +#include "includes.h" + +#if defined(GSSAPI) && defined(WITH_OPENSSL) + +#include "includes.h" + +#include <openssl/crypto.h> +#include <openssl/bn.h> + +#include <string.h> + +#include "xmalloc.h" +#include "sshbuf.h" +#include "ssh2.h" +#include "sshkey.h" +#include "cipher.h" +#include "kex.h" +#include "log.h" +#include "packet.h" +#include "dh.h" +#include "digest.h" +#include "ssherr.h" + +#include "ssh-gss.h" + +int +kexgss_client(struct ssh *ssh) +{ + struct kex *kex = ssh->kex; + gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER, + recv_tok = GSS_C_EMPTY_BUFFER, + gssbuf, msg_tok = GSS_C_EMPTY_BUFFER, *token_ptr; + Gssctxt *ctxt; + OM_uint32 maj_status, min_status, ret_flags; + struct sshbuf *server_blob = NULL; + struct sshbuf *shared_secret = NULL; + struct sshbuf *server_host_key_blob = NULL; + struct sshbuf *empty = NULL; + u_char *msg; + int type = 0; + int first = 1; + u_char hash[SSH_DIGEST_MAX_LENGTH]; + size_t hashlen; + u_char c; + int r; + + /* Initialise our GSSAPI world */ + ssh_gssapi_build_ctx(&ctxt); + if (ssh_gssapi_id_kex(ctxt, kex->name, kex->kex_type) + == GSS_C_NO_OID) + fatal("Couldn't identify host exchange"); + + if (ssh_gssapi_import_name(ctxt, kex->gss_host)) + fatal("Couldn't import hostname"); + + if (kex->gss_client && + ssh_gssapi_client_identity(ctxt, kex->gss_client)) + fatal("Couldn't acquire client credentials"); + + /* Step 1 */ + switch (kex->kex_type) { + case KEX_GSS_GRP1_SHA1: + case KEX_GSS_GRP14_SHA1: + case KEX_GSS_GRP14_SHA256: + case KEX_GSS_GRP16_SHA512: + r = kex_dh_keypair(kex); + break; + case KEX_GSS_NISTP256_SHA256: + r = kex_ecdh_keypair(kex); + break; + case KEX_GSS_C25519_SHA256: + r = kex_c25519_keypair(kex); + break; + default: + fatal_f("Unexpected KEX type %d", kex->kex_type); + } + if (r != 0) { + ssh_gssapi_delete_ctx(&ctxt); + return r; + } + + token_ptr = GSS_C_NO_BUFFER; + + do { + debug("Calling gss_init_sec_context"); + + maj_status = ssh_gssapi_init_ctx(ctxt, + kex->gss_deleg_creds, token_ptr, &send_tok, + &ret_flags); + + if (GSS_ERROR(maj_status)) { + /* XXX Useles code: Missing send? */ + if (send_tok.length != 0) { + if ((r = sshpkt_start(ssh, + SSH2_MSG_KEXGSS_CONTINUE)) != 0 || + (r = sshpkt_put_string(ssh, send_tok.value, + send_tok.length)) != 0) + fatal("sshpkt failed: %s", ssh_err(r)); + } + fatal("gss_init_context failed"); + } + + /* If we've got an old receive buffer get rid of it */ + if (token_ptr != GSS_C_NO_BUFFER) + gss_release_buffer(&min_status, &recv_tok); + + if (maj_status == GSS_S_COMPLETE) { + /* If mutual state flag is not true, kex fails */ + if (!(ret_flags & GSS_C_MUTUAL_FLAG)) + fatal("Mutual authentication failed"); + + /* If integ avail flag is not true kex fails */ + if (!(ret_flags & GSS_C_INTEG_FLAG)) + fatal("Integrity check failed"); + } + + /* + * If we have data to send, then the last message that we + * received cannot have been a 'complete'. + */ + if (send_tok.length != 0) { + if (first) { + if ((r = sshpkt_start(ssh, SSH2_MSG_KEXGSS_INIT)) != 0 || + (r = sshpkt_put_string(ssh, send_tok.value, + send_tok.length)) != 0 || + (r = sshpkt_put_stringb(ssh, kex->client_pub)) != 0) + fatal("failed to construct packet: %s", ssh_err(r)); + first = 0; + } else { + if ((r = sshpkt_start(ssh, SSH2_MSG_KEXGSS_CONTINUE)) != 0 || + (r = sshpkt_put_string(ssh, send_tok.value, + send_tok.length)) != 0) + fatal("failed to construct packet: %s", ssh_err(r)); + } + if ((r = sshpkt_send(ssh)) != 0) + fatal("failed to send packet: %s", ssh_err(r)); + gss_release_buffer(&min_status, &send_tok); + + /* If we've sent them data, they should reply */ + do { + type = ssh_packet_read(ssh); + if (type == SSH2_MSG_KEXGSS_HOSTKEY) { + u_char *tmp = NULL; + size_t tmp_len = 0; + + debug("Received KEXGSS_HOSTKEY"); + if (server_host_key_blob) + fatal("Server host key received more than once"); + if ((r = sshpkt_get_string(ssh, &tmp, &tmp_len)) != 0) + fatal("Failed to read server host key: %s", ssh_err(r)); + if ((server_host_key_blob = sshbuf_from(tmp, tmp_len)) == NULL) + fatal("sshbuf_from failed"); + } + } while (type == SSH2_MSG_KEXGSS_HOSTKEY); + + switch (type) { + case SSH2_MSG_KEXGSS_CONTINUE: + debug("Received GSSAPI_CONTINUE"); + if (maj_status == GSS_S_COMPLETE) + fatal("GSSAPI Continue received from server when complete"); + if ((r = ssh_gssapi_sshpkt_get_buffer_desc(ssh, + &recv_tok)) != 0 || + (r = sshpkt_get_end(ssh)) != 0) + fatal("Failed to read token: %s", ssh_err(r)); + break; + case SSH2_MSG_KEXGSS_COMPLETE: + debug("Received GSSAPI_COMPLETE"); + if (msg_tok.value != NULL) + fatal("Received GSSAPI_COMPLETE twice?"); + if ((r = sshpkt_getb_froms(ssh, &server_blob)) != 0 || + (r = ssh_gssapi_sshpkt_get_buffer_desc(ssh, + &msg_tok)) != 0) + fatal("Failed to read message: %s", ssh_err(r)); + + /* Is there a token included? */ + if ((r = sshpkt_get_u8(ssh, &c)) != 0) + fatal("sshpkt failed: %s", ssh_err(r)); + if (c) { + if ((r = ssh_gssapi_sshpkt_get_buffer_desc( + ssh, &recv_tok)) != 0) + fatal("Failed to read token: %s", ssh_err(r)); + /* If we're already complete - protocol error */ + if (maj_status == GSS_S_COMPLETE) + sshpkt_disconnect(ssh, "Protocol error: received token when complete"); + } else { + /* No token included */ + if (maj_status != GSS_S_COMPLETE) + sshpkt_disconnect(ssh, "Protocol error: did not receive final token"); + } + if ((r = sshpkt_get_end(ssh)) != 0) { + fatal("Expecting end of packet."); + } + break; + case SSH2_MSG_KEXGSS_ERROR: + debug("Received Error"); + if ((r = sshpkt_get_u32(ssh, &maj_status)) != 0 || + (r = sshpkt_get_u32(ssh, &min_status)) != 0 || + (r = sshpkt_get_string(ssh, &msg, NULL)) != 0 || + (r = sshpkt_get_string(ssh, NULL, NULL)) != 0 || /* lang tag */ + (r = sshpkt_get_end(ssh)) != 0) + fatal("sshpkt_get failed: %s", ssh_err(r)); + fatal("GSSAPI Error: \n%.400s", msg); + default: + sshpkt_disconnect(ssh, "Protocol error: didn't expect packet type %d", + type); + } + token_ptr = &recv_tok; + } else { + /* No data, and not complete */ + if (maj_status != GSS_S_COMPLETE) + fatal("Not complete, and no token output"); + } + } while (maj_status & GSS_S_CONTINUE_NEEDED); + + /* + * We _must_ have received a COMPLETE message in reply from the + * server, which will have set server_blob and msg_tok + */ + + if (type != SSH2_MSG_KEXGSS_COMPLETE) + fatal("Didn't receive a SSH2_MSG_KEXGSS_COMPLETE when I expected it"); + + /* compute shared secret */ + switch (kex->kex_type) { + case KEX_GSS_GRP1_SHA1: + case KEX_GSS_GRP14_SHA1: + case KEX_GSS_GRP14_SHA256: + case KEX_GSS_GRP16_SHA512: + r = kex_dh_dec(kex, server_blob, &shared_secret); + break; + case KEX_GSS_C25519_SHA256: + if (sshbuf_ptr(server_blob)[sshbuf_len(server_blob)] & 0x80) + fatal("The received key has MSB of last octet set!"); + r = kex_c25519_dec(kex, server_blob, &shared_secret); + break; + case KEX_GSS_NISTP256_SHA256: + if (sshbuf_len(server_blob) != 65) + fatal("The received NIST-P256 key did not match" + "expected length (expected 65, got %zu)", sshbuf_len(server_blob)); + + if (sshbuf_ptr(server_blob)[0] != POINT_CONVERSION_UNCOMPRESSED) + fatal("The received NIST-P256 key does not have first octet 0x04"); + + r = kex_ecdh_dec(kex, server_blob, &shared_secret); + break; + default: + r = SSH_ERR_INVALID_ARGUMENT; + break; + } + if (r != 0) + goto out; + + if ((empty = sshbuf_new()) == NULL) { + r = SSH_ERR_ALLOC_FAIL; + goto out; + } + + hashlen = sizeof(hash); + if ((r = kex_gen_hash( + kex->hash_alg, + kex->client_version, + kex->server_version, + kex->my, + kex->peer, + (server_host_key_blob ? server_host_key_blob : empty), + kex->client_pub, + server_blob, + shared_secret, + hash, &hashlen)) != 0) + fatal_f("Unexpected KEX type %d", kex->kex_type); + + gssbuf.value = hash; + gssbuf.length = hashlen; + + /* Verify that the hash matches the MIC we just got. */ + if (GSS_ERROR(ssh_gssapi_checkmic(ctxt, &gssbuf, &msg_tok))) + sshpkt_disconnect(ssh, "Hash's MIC didn't verify"); + + gss_release_buffer(&min_status, &msg_tok); + + if (kex->gss_deleg_creds) + ssh_gssapi_credentials_updated(ctxt); + + if (gss_kex_context == NULL) + gss_kex_context = ctxt; + else + ssh_gssapi_delete_ctx(&ctxt); + + if ((r = kex_derive_keys(ssh, hash, hashlen, shared_secret)) == 0) + r = kex_send_newkeys(ssh); + +out: + explicit_bzero(hash, sizeof(hash)); + explicit_bzero(kex->c25519_client_key, sizeof(kex->c25519_client_key)); + sshbuf_free(empty); + sshbuf_free(server_host_key_blob); + sshbuf_free(server_blob); + sshbuf_free(shared_secret); + sshbuf_free(kex->client_pub); + kex->client_pub = NULL; + return r; +} + +int +kexgssgex_client(struct ssh *ssh) +{ + struct kex *kex = ssh->kex; + gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER, + recv_tok = GSS_C_EMPTY_BUFFER, gssbuf, + msg_tok = GSS_C_EMPTY_BUFFER, *token_ptr; + Gssctxt *ctxt; + OM_uint32 maj_status, min_status, ret_flags; + struct sshbuf *shared_secret = NULL; + BIGNUM *p = NULL; + BIGNUM *g = NULL; + struct sshbuf *buf = NULL; + struct sshbuf *server_host_key_blob = NULL; + struct sshbuf *server_blob = NULL; + BIGNUM *dh_server_pub = NULL; + u_char *msg; + int type = 0; + int first = 1; + u_char hash[SSH_DIGEST_MAX_LENGTH]; + size_t hashlen; + const BIGNUM *pub_key, *dh_p, *dh_g; + int nbits = 0, min = DH_GRP_MIN, max = DH_GRP_MAX; + struct sshbuf *empty = NULL; + u_char c; + int r; + + /* Initialise our GSSAPI world */ + ssh_gssapi_build_ctx(&ctxt); + if (ssh_gssapi_id_kex(ctxt, kex->name, kex->kex_type) + == GSS_C_NO_OID) + fatal("Couldn't identify host exchange"); + + if (ssh_gssapi_import_name(ctxt, kex->gss_host)) + fatal("Couldn't import hostname"); + + if (kex->gss_client && + ssh_gssapi_client_identity(ctxt, kex->gss_client)) + fatal("Couldn't acquire client credentials"); + + debug("Doing group exchange"); + nbits = dh_estimate(kex->dh_need * 8); + + kex->min = DH_GRP_MIN; + kex->max = DH_GRP_MAX; + kex->nbits = nbits; + if ((r = sshpkt_start(ssh, SSH2_MSG_KEXGSS_GROUPREQ)) != 0 || + (r = sshpkt_put_u32(ssh, min)) != 0 || + (r = sshpkt_put_u32(ssh, nbits)) != 0 || + (r = sshpkt_put_u32(ssh, max)) != 0 || + (r = sshpkt_send(ssh)) != 0) + fatal("Failed to construct a packet: %s", ssh_err(r)); + + if ((r = ssh_packet_read_expect(ssh, SSH2_MSG_KEXGSS_GROUP)) != 0) + fatal("Error: %s", ssh_err(r)); + + if ((r = sshpkt_get_bignum2(ssh, &p)) != 0 || + (r = sshpkt_get_bignum2(ssh, &g)) != 0 || + (r = sshpkt_get_end(ssh)) != 0) + fatal("shpkt_get_bignum2 failed: %s", ssh_err(r)); + + if (BN_num_bits(p) < min || BN_num_bits(p) > max) + fatal("GSSGRP_GEX group out of range: %d !< %d !< %d", + min, BN_num_bits(p), max); + + if ((kex->dh = dh_new_group(g, p)) == NULL) + fatal("dn_new_group() failed"); + p = g = NULL; /* belong to kex->dh now */ + + if ((r = dh_gen_key(kex->dh, kex->we_need * 8)) != 0) + goto out; + DH_get0_key(kex->dh, &pub_key, NULL); + + token_ptr = GSS_C_NO_BUFFER; + + do { + /* Step 2 - call GSS_Init_sec_context() */ + debug("Calling gss_init_sec_context"); + + maj_status = ssh_gssapi_init_ctx(ctxt, + kex->gss_deleg_creds, token_ptr, &send_tok, + &ret_flags); + + if (GSS_ERROR(maj_status)) { + /* XXX Useles code: Missing send? */ + if (send_tok.length != 0) { + if ((r = sshpkt_start(ssh, + SSH2_MSG_KEXGSS_CONTINUE)) != 0 || + (r = sshpkt_put_string(ssh, send_tok.value, + send_tok.length)) != 0) + fatal("sshpkt failed: %s", ssh_err(r)); + } + fatal("gss_init_context failed"); + } + + /* If we've got an old receive buffer get rid of it */ + if (token_ptr != GSS_C_NO_BUFFER) + gss_release_buffer(&min_status, &recv_tok); + + if (maj_status == GSS_S_COMPLETE) { + /* If mutual state flag is not true, kex fails */ + if (!(ret_flags & GSS_C_MUTUAL_FLAG)) + fatal("Mutual authentication failed"); + + /* If integ avail flag is not true kex fails */ + if (!(ret_flags & GSS_C_INTEG_FLAG)) + fatal("Integrity check failed"); + } + + /* + * If we have data to send, then the last message that we + * received cannot have been a 'complete'. + */ + if (send_tok.length != 0) { + if (first) { + if ((r = sshpkt_start(ssh, SSH2_MSG_KEXGSS_INIT)) != 0 || + (r = sshpkt_put_string(ssh, send_tok.value, + send_tok.length)) != 0 || + (r = sshpkt_put_bignum2(ssh, pub_key)) != 0) + fatal("sshpkt failed: %s", ssh_err(r)); + first = 0; + } else { + if ((r = sshpkt_start(ssh, SSH2_MSG_KEXGSS_CONTINUE)) != 0 || + (r = sshpkt_put_string(ssh,send_tok.value, + send_tok.length)) != 0) + fatal("sshpkt failed: %s", ssh_err(r)); + } + if ((r = sshpkt_send(ssh)) != 0) + fatal("sshpkt_send failed: %s", ssh_err(r)); + gss_release_buffer(&min_status, &send_tok); + + /* If we've sent them data, they should reply */ + do { + type = ssh_packet_read(ssh); + if (type == SSH2_MSG_KEXGSS_HOSTKEY) { + u_char *tmp = NULL; + size_t tmp_len = 0; + + debug("Received KEXGSS_HOSTKEY"); + if (server_host_key_blob) + fatal("Server host key received more than once"); + if ((r = sshpkt_get_string(ssh, &tmp, &tmp_len)) != 0) + fatal("sshpkt failed: %s", ssh_err(r)); + if ((server_host_key_blob = sshbuf_from(tmp, tmp_len)) == NULL) + fatal("sshbuf_from failed"); + } + } while (type == SSH2_MSG_KEXGSS_HOSTKEY); + + switch (type) { + case SSH2_MSG_KEXGSS_CONTINUE: + debug("Received GSSAPI_CONTINUE"); + if (maj_status == GSS_S_COMPLETE) + fatal("GSSAPI Continue received from server when complete"); + if ((r = ssh_gssapi_sshpkt_get_buffer_desc(ssh, + &recv_tok)) != 0 || + (r = sshpkt_get_end(ssh)) != 0) + fatal("sshpkt failed: %s", ssh_err(r)); + break; + case SSH2_MSG_KEXGSS_COMPLETE: + debug("Received GSSAPI_COMPLETE"); + if (msg_tok.value != NULL) + fatal("Received GSSAPI_COMPLETE twice?"); + if ((r = sshpkt_getb_froms(ssh, &server_blob)) != 0 || + (r = ssh_gssapi_sshpkt_get_buffer_desc(ssh, + &msg_tok)) != 0) + fatal("sshpkt failed: %s", ssh_err(r)); + + /* Is there a token included? */ + if ((r = sshpkt_get_u8(ssh, &c)) != 0) + fatal("sshpkt failed: %s", ssh_err(r)); + if (c) { + if ((r = ssh_gssapi_sshpkt_get_buffer_desc( + ssh, &recv_tok)) != 0 || + (r = sshpkt_get_end(ssh)) != 0) + fatal("sshpkt failed: %s", ssh_err(r)); + /* If we're already complete - protocol error */ + if (maj_status == GSS_S_COMPLETE) + sshpkt_disconnect(ssh, "Protocol error: received token when complete"); + } else { + /* No token included */ + if (maj_status != GSS_S_COMPLETE) + sshpkt_disconnect(ssh, "Protocol error: did not receive final token"); + } + break; + case SSH2_MSG_KEXGSS_ERROR: + debug("Received Error"); + if ((r = sshpkt_get_u32(ssh, &maj_status)) != 0 || + (r = sshpkt_get_u32(ssh, &min_status)) != 0 || + (r = sshpkt_get_string(ssh, &msg, NULL)) != 0 || + (r = sshpkt_get_string(ssh, NULL, NULL)) != 0 || /* lang tag */ + (r = sshpkt_get_end(ssh)) != 0) + fatal("sshpkt failed: %s", ssh_err(r)); + fatal("GSSAPI Error: \n%.400s", msg); + default: + sshpkt_disconnect(ssh, "Protocol error: didn't expect packet type %d", + type); + } + token_ptr = &recv_tok; + } else { + /* No data, and not complete */ + if (maj_status != GSS_S_COMPLETE) + fatal("Not complete, and no token output"); + } + } while (maj_status & GSS_S_CONTINUE_NEEDED); + + /* + * We _must_ have received a COMPLETE message in reply from the + * server, which will have set dh_server_pub and msg_tok + */ + + if (type != SSH2_MSG_KEXGSS_COMPLETE) + fatal("Didn't receive a SSH2_MSG_KEXGSS_COMPLETE when I expected it"); + + /* 7. C verifies that the key Q_S is valid */ + /* 8. C computes shared secret */ + if ((buf = sshbuf_new()) == NULL || + (r = sshbuf_put_stringb(buf, server_blob)) != 0 || + (r = sshbuf_get_bignum2(buf, &dh_server_pub)) != 0) + goto out; + sshbuf_free(buf); + buf = NULL; + + if ((shared_secret = sshbuf_new()) == NULL) { + r = SSH_ERR_ALLOC_FAIL; + goto out; + } + + if ((r = kex_dh_compute_key(kex, dh_server_pub, shared_secret)) != 0) + goto out; + if ((empty = sshbuf_new()) == NULL) { + r = SSH_ERR_ALLOC_FAIL; + goto out; + } + + DH_get0_pqg(kex->dh, &dh_p, NULL, &dh_g); + hashlen = sizeof(hash); + if ((r = kexgex_hash( + kex->hash_alg, + kex->client_version, + kex->server_version, + kex->my, + kex->peer, + (server_host_key_blob ? server_host_key_blob : empty), + kex->min, kex->nbits, kex->max, + dh_p, dh_g, + pub_key, + dh_server_pub, + sshbuf_ptr(shared_secret), sshbuf_len(shared_secret), + hash, &hashlen)) != 0) + fatal("Failed to calculate hash: %s", ssh_err(r)); + + gssbuf.value = hash; + gssbuf.length = hashlen; + + /* Verify that the hash matches the MIC we just got. */ + if (GSS_ERROR(ssh_gssapi_checkmic(ctxt, &gssbuf, &msg_tok))) + sshpkt_disconnect(ssh, "Hash's MIC didn't verify"); + + gss_release_buffer(&min_status, &msg_tok); + + if (kex->gss_deleg_creds) + ssh_gssapi_credentials_updated(ctxt); + + if (gss_kex_context == NULL) + gss_kex_context = ctxt; + else + ssh_gssapi_delete_ctx(&ctxt); + + /* Finally derive the keys and send them */ + if ((r = kex_derive_keys(ssh, hash, hashlen, shared_secret)) == 0) + r = kex_send_newkeys(ssh); +out: + sshbuf_free(buf); + sshbuf_free(server_blob); + sshbuf_free(empty); + explicit_bzero(hash, sizeof(hash)); + DH_free(kex->dh); + kex->dh = NULL; + BN_clear_free(dh_server_pub); + sshbuf_free(shared_secret); + sshbuf_free(server_host_key_blob); + return r; +} + +#endif /* defined(GSSAPI) && defined(WITH_OPENSSL) */ diff --git a/kexgsss.c b/kexgsss.c new file mode 100644 index 00000000..60bc02de --- /dev/null +++ b/kexgsss.c @@ -0,0 +1,482 @@ +/* + * Copyright (c) 2001-2009 Simon Wilkinson. All rights reserved. + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions + * are met: + * 1. Redistributions of source code must retain the above copyright + * notice, this list of conditions and the following disclaimer. + * 2. Redistributions in binary form must reproduce the above copyright + * notice, this list of conditions and the following disclaimer in the + * documentation and/or other materials provided with the distribution. + * + * THIS SOFTWARE IS PROVIDED BY THE AUTHOR `AS IS'' AND ANY EXPRESS OR + * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES + * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. + * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, + * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT + * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, + * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY + * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT + * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF + * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. + */ + +#include "includes.h" + +#if defined(GSSAPI) && defined(WITH_OPENSSL) + +#include <string.h> + +#include <openssl/crypto.h> +#include <openssl/bn.h> + +#include "xmalloc.h" +#include "sshbuf.h" +#include "ssh2.h" +#include "sshkey.h" +#include "cipher.h" +#include "kex.h" +#include "log.h" +#include "packet.h" +#include "dh.h" +#include "ssh-gss.h" +#include "monitor_wrap.h" +#include "misc.h" /* servconf.h needs misc.h for struct ForwardOptions */ +#include "servconf.h" +#include "ssh-gss.h" +#include "digest.h" +#include "ssherr.h" + +extern ServerOptions options; + +int +kexgss_server(struct ssh *ssh) +{ + struct kex *kex = ssh->kex; + OM_uint32 maj_status, min_status; + + /* + * Some GSSAPI implementations use the input value of ret_flags (an + * output variable) as a means of triggering mechanism specific + * features. Initializing it to zero avoids inadvertently + * activating this non-standard behaviour. + */ + + OM_uint32 ret_flags = 0; + gss_buffer_desc gssbuf = {0, NULL}, recv_tok, msg_tok; + gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER; + Gssctxt *ctxt = NULL; + struct sshbuf *shared_secret = NULL; + struct sshbuf *client_pubkey = NULL; + struct sshbuf *server_pubkey = NULL; + struct sshbuf *empty = sshbuf_new(); + int type = 0; + gss_OID oid; + char *mechs; + u_char hash[SSH_DIGEST_MAX_LENGTH]; + size_t hashlen; + int r; + + /* Initialise GSSAPI */ + + /* If we're rekeying, privsep means that some of the private structures + * in the GSSAPI code are no longer available. This kludges them back + * into life + */ + if (!ssh_gssapi_oid_table_ok()) { + mechs = ssh_gssapi_server_mechanisms(); + free(mechs); + } + + debug2_f("Identifying %s", kex->name); + oid = ssh_gssapi_id_kex(NULL, kex->name, kex->kex_type); + if (oid == GSS_C_NO_OID) + fatal("Unknown gssapi mechanism"); + + debug2_f("Acquiring credentials"); + + if (GSS_ERROR(mm_ssh_gssapi_server_ctx(&ctxt, oid))) + fatal("Unable to acquire credentials for the server"); + + do { + debug("Wait SSH2_MSG_KEXGSS_INIT"); + type = ssh_packet_read(ssh); + switch(type) { + case SSH2_MSG_KEXGSS_INIT: + if (gssbuf.value != NULL) + fatal("Received KEXGSS_INIT after initialising"); + if ((r = ssh_gssapi_sshpkt_get_buffer_desc(ssh, + &recv_tok)) != 0 || + (r = sshpkt_getb_froms(ssh, &client_pubkey)) != 0 || + (r = sshpkt_get_end(ssh)) != 0) + fatal("sshpkt failed: %s", ssh_err(r)); + + switch (kex->kex_type) { + case KEX_GSS_GRP1_SHA1: + case KEX_GSS_GRP14_SHA1: + case KEX_GSS_GRP14_SHA256: + case KEX_GSS_GRP16_SHA512: + r = kex_dh_enc(kex, client_pubkey, &server_pubkey, + &shared_secret); + break; + case KEX_GSS_NISTP256_SHA256: + r = kex_ecdh_enc(kex, client_pubkey, &server_pubkey, + &shared_secret); + break; + case KEX_GSS_C25519_SHA256: + r = kex_c25519_enc(kex, client_pubkey, &server_pubkey, + &shared_secret); + break; + default: + fatal_f("Unexpected KEX type %d", kex->kex_type); + } + if (r != 0) + goto out; + + /* Send SSH_MSG_KEXGSS_HOSTKEY here, if we want */ + + /* Calculate the hash early so we can free the + * client_pubkey, which has reference to the parent + * buffer state->incoming_packet + */ + hashlen = sizeof(hash); + if ((r = kex_gen_hash( + kex->hash_alg, + kex->client_version, + kex->server_version, + kex->peer, + kex->my, + empty, + client_pubkey, + server_pubkey, + shared_secret, + hash, &hashlen)) != 0) + goto out; + + gssbuf.value = hash; + gssbuf.length = hashlen; + + sshbuf_free(client_pubkey); + client_pubkey = NULL; + + break; + case SSH2_MSG_KEXGSS_CONTINUE: + if ((r = ssh_gssapi_sshpkt_get_buffer_desc(ssh, + &recv_tok)) != 0 || + (r = sshpkt_get_end(ssh)) != 0) + fatal("sshpkt failed: %s", ssh_err(r)); + break; + default: + sshpkt_disconnect(ssh, + "Protocol error: didn't expect packet type %d", + type); + } + + maj_status = mm_ssh_gssapi_accept_ctx(ctxt, &recv_tok, + &send_tok, &ret_flags); + + gss_release_buffer(&min_status, &recv_tok); + + if (maj_status != GSS_S_COMPLETE && send_tok.length == 0) + fatal("Zero length token output when incomplete"); + + if (gssbuf.value == NULL) + fatal("No client public key"); + + if (maj_status & GSS_S_CONTINUE_NEEDED) { + debug("Sending GSSAPI_CONTINUE"); + if ((r = sshpkt_start(ssh, SSH2_MSG_KEXGSS_CONTINUE)) != 0 || + (r = sshpkt_put_string(ssh, send_tok.value, send_tok.length)) != 0 || + (r = sshpkt_send(ssh)) != 0) + fatal("sshpkt failed: %s", ssh_err(r)); + gss_release_buffer(&min_status, &send_tok); + } + } while (maj_status & GSS_S_CONTINUE_NEEDED); + + if (GSS_ERROR(maj_status)) { + if (send_tok.length > 0) { + if ((r = sshpkt_start(ssh, SSH2_MSG_KEXGSS_CONTINUE)) != 0 || + (r = sshpkt_put_string(ssh, send_tok.value, send_tok.length)) != 0 || + (r = sshpkt_send(ssh)) != 0) + fatal("sshpkt failed: %s", ssh_err(r)); + } + fatal("accept_ctx died"); + } + + if (!(ret_flags & GSS_C_MUTUAL_FLAG)) + fatal("Mutual Authentication flag wasn't set"); + + if (!(ret_flags & GSS_C_INTEG_FLAG)) + fatal("Integrity flag wasn't set"); + + if (GSS_ERROR(mm_ssh_gssapi_sign(ctxt, &gssbuf, &msg_tok))) + fatal("Couldn't get MIC"); + + if ((r = sshpkt_start(ssh, SSH2_MSG_KEXGSS_COMPLETE)) != 0 || + (r = sshpkt_put_stringb(ssh, server_pubkey)) != 0 || + (r = sshpkt_put_string(ssh, msg_tok.value, msg_tok.length)) != 0) + fatal("sshpkt failed: %s", ssh_err(r)); + + if (send_tok.length != 0) { + if ((r = sshpkt_put_u8(ssh, 1)) != 0 || /* true */ + (r = sshpkt_put_string(ssh, send_tok.value, send_tok.length)) != 0) + fatal("sshpkt failed: %s", ssh_err(r)); + } else { + if ((r = sshpkt_put_u8(ssh, 0)) != 0) /* false */ + fatal("sshpkt failed: %s", ssh_err(r)); + } + if ((r = sshpkt_send(ssh)) != 0) + fatal("sshpkt_send failed: %s", ssh_err(r)); + + gss_release_buffer(&min_status, &send_tok); + gss_release_buffer(&min_status, &msg_tok); + + if (gss_kex_context == NULL) + gss_kex_context = ctxt; + else + ssh_gssapi_delete_ctx(&ctxt); + + if ((r = kex_derive_keys(ssh, hash, hashlen, shared_secret)) == 0) + r = kex_send_newkeys(ssh); + + /* If this was a rekey, then save out any delegated credentials we + * just exchanged. */ + if (options.gss_store_rekey) + ssh_gssapi_rekey_creds(); +out: + sshbuf_free(empty); + explicit_bzero(hash, sizeof(hash)); + sshbuf_free(shared_secret); + sshbuf_free(client_pubkey); + sshbuf_free(server_pubkey); + return r; +} + +int +kexgssgex_server(struct ssh *ssh) +{ + struct kex *kex = ssh->kex; + OM_uint32 maj_status, min_status; + + /* + * Some GSSAPI implementations use the input value of ret_flags (an + * output variable) as a means of triggering mechanism specific + * features. Initializing it to zero avoids inadvertently + * activating this non-standard behaviour. + */ + + OM_uint32 ret_flags = 0; + gss_buffer_desc gssbuf, recv_tok, msg_tok; + gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER; + Gssctxt *ctxt = NULL; + struct sshbuf *shared_secret = NULL; + int type = 0; + gss_OID oid; + char *mechs; + u_char hash[SSH_DIGEST_MAX_LENGTH]; + size_t hashlen; + BIGNUM *dh_client_pub = NULL; + const BIGNUM *pub_key, *dh_p, *dh_g; + int min = -1, max = -1, nbits = -1; + int cmin = -1, cmax = -1; /* client proposal */ + struct sshbuf *empty = sshbuf_new(); + int r; + + /* Initialise GSSAPI */ + + /* If we're rekeying, privsep means that some of the private structures + * in the GSSAPI code are no longer available. This kludges them back + * into life + */ + if (!ssh_gssapi_oid_table_ok()) + if ((mechs = ssh_gssapi_server_mechanisms())) + free(mechs); + + debug2_f("Identifying %s", kex->name); + oid = ssh_gssapi_id_kex(NULL, kex->name, kex->kex_type); + if (oid == GSS_C_NO_OID) + fatal("Unknown gssapi mechanism"); + + debug2_f("Acquiring credentials"); + + if (GSS_ERROR(mm_ssh_gssapi_server_ctx(&ctxt, oid))) + fatal("Unable to acquire credentials for the server"); + + /* 5. S generates an ephemeral key pair (do the allocations early) */ + debug("Doing group exchange"); + ssh_packet_read_expect(ssh, SSH2_MSG_KEXGSS_GROUPREQ); + /* store client proposal to provide valid signature */ + if ((r = sshpkt_get_u32(ssh, &cmin)) != 0 || + (r = sshpkt_get_u32(ssh, &nbits)) != 0 || + (r = sshpkt_get_u32(ssh, &cmax)) != 0 || + (r = sshpkt_get_end(ssh)) != 0) + fatal("sshpkt failed: %s", ssh_err(r)); + kex->nbits = nbits; + kex->min = cmin; + kex->max = cmax; + min = MAX(DH_GRP_MIN, cmin); + max = MIN(DH_GRP_MAX, cmax); + nbits = MAXIMUM(DH_GRP_MIN, nbits); + nbits = MINIMUM(DH_GRP_MAX, nbits); + if (max < min || nbits < min || max < nbits) + fatal("GSS_GEX, bad parameters: %d !< %d !< %d", + min, nbits, max); + kex->dh = mm_choose_dh(min, nbits, max); + if (kex->dh == NULL) { + sshpkt_disconnect(ssh, "Protocol error: no matching group found"); + fatal("Protocol error: no matching group found"); + } + + DH_get0_pqg(kex->dh, &dh_p, NULL, &dh_g); + if ((r = sshpkt_start(ssh, SSH2_MSG_KEXGSS_GROUP)) != 0 || + (r = sshpkt_put_bignum2(ssh, dh_p)) != 0 || + (r = sshpkt_put_bignum2(ssh, dh_g)) != 0 || + (r = sshpkt_send(ssh)) != 0) + fatal("sshpkt failed: %s", ssh_err(r)); + + if ((r = ssh_packet_write_wait(ssh)) != 0) + fatal("ssh_packet_write_wait: %s", ssh_err(r)); + + /* Compute our exchange value in parallel with the client */ + if ((r = dh_gen_key(kex->dh, kex->we_need * 8)) != 0) + goto out; + + do { + debug("Wait SSH2_MSG_GSSAPI_INIT"); + type = ssh_packet_read(ssh); + switch(type) { + case SSH2_MSG_KEXGSS_INIT: + if (dh_client_pub != NULL) + fatal("Received KEXGSS_INIT after initialising"); + if ((r = ssh_gssapi_sshpkt_get_buffer_desc(ssh, + &recv_tok)) != 0 || + (r = sshpkt_get_bignum2(ssh, &dh_client_pub)) != 0 || + (r = sshpkt_get_end(ssh)) != 0) + fatal("sshpkt failed: %s", ssh_err(r)); + + /* Send SSH_MSG_KEXGSS_HOSTKEY here, if we want */ + break; + case SSH2_MSG_KEXGSS_CONTINUE: + if ((r = ssh_gssapi_sshpkt_get_buffer_desc(ssh, + &recv_tok)) != 0 || + (r = sshpkt_get_end(ssh)) != 0) + fatal("sshpkt failed: %s", ssh_err(r)); + break; + default: + sshpkt_disconnect(ssh, + "Protocol error: didn't expect packet type %d", + type); + } + + maj_status = mm_ssh_gssapi_accept_ctx(ctxt, &recv_tok, + &send_tok, &ret_flags); + + gss_release_buffer(&min_status, &recv_tok); + + if (maj_status != GSS_S_COMPLETE && send_tok.length == 0) + fatal("Zero length token output when incomplete"); + + if (dh_client_pub == NULL) + fatal("No client public key"); + + if (maj_status & GSS_S_CONTINUE_NEEDED) { + debug("Sending GSSAPI_CONTINUE"); + if ((r = sshpkt_start(ssh, SSH2_MSG_KEXGSS_CONTINUE)) != 0 || + (r = sshpkt_put_string(ssh, send_tok.value, send_tok.length)) != 0 || + (r = sshpkt_send(ssh)) != 0) + fatal("sshpkt failed: %s", ssh_err(r)); + gss_release_buffer(&min_status, &send_tok); + } + } while (maj_status & GSS_S_CONTINUE_NEEDED); + + if (GSS_ERROR(maj_status)) { + if (send_tok.length > 0) { + if ((r = sshpkt_start(ssh, SSH2_MSG_KEXGSS_CONTINUE)) != 0 || + (r = sshpkt_put_string(ssh, send_tok.value, send_tok.length)) != 0 || + (r = sshpkt_send(ssh)) != 0) + fatal("sshpkt failed: %s", ssh_err(r)); + } + fatal("accept_ctx died"); + } + + if (!(ret_flags & GSS_C_MUTUAL_FLAG)) + fatal("Mutual Authentication flag wasn't set"); + + if (!(ret_flags & GSS_C_INTEG_FLAG)) + fatal("Integrity flag wasn't set"); + + /* calculate shared secret */ + if ((shared_secret = sshbuf_new()) == NULL) { + r = SSH_ERR_ALLOC_FAIL; + goto out; + } + if ((r = kex_dh_compute_key(kex, dh_client_pub, shared_secret)) != 0) + goto out; + + DH_get0_key(kex->dh, &pub_key, NULL); + DH_get0_pqg(kex->dh, &dh_p, NULL, &dh_g); + hashlen = sizeof(hash); + if ((r = kexgex_hash( + kex->hash_alg, + kex->client_version, + kex->server_version, + kex->peer, + kex->my, + empty, + cmin, nbits, cmax, + dh_p, dh_g, + dh_client_pub, + pub_key, + sshbuf_ptr(shared_secret), sshbuf_len(shared_secret), + hash, &hashlen)) != 0) + fatal("kexgex_hash failed: %s", ssh_err(r)); + + gssbuf.value = hash; + gssbuf.length = hashlen; + + if (GSS_ERROR(mm_ssh_gssapi_sign(ctxt, &gssbuf, &msg_tok))) + fatal("Couldn't get MIC"); + + if ((r = sshpkt_start(ssh, SSH2_MSG_KEXGSS_COMPLETE)) != 0 || + (r = sshpkt_put_bignum2(ssh, pub_key)) != 0 || + (r = sshpkt_put_string(ssh, msg_tok.value, msg_tok.length)) != 0) + fatal("sshpkt failed: %s", ssh_err(r)); + + if (send_tok.length != 0) { + if ((r = sshpkt_put_u8(ssh, 1)) != 0 || /* true */ + (r = sshpkt_put_string(ssh, send_tok.value, send_tok.length)) != 0) + fatal("sshpkt failed: %s", ssh_err(r)); + } else { + if ((r = sshpkt_put_u8(ssh, 0)) != 0) /* false */ + fatal("sshpkt failed: %s", ssh_err(r)); + } + if ((r = sshpkt_send(ssh)) != 0) + fatal("sshpkt failed: %s", ssh_err(r)); + + gss_release_buffer(&min_status, &send_tok); + gss_release_buffer(&min_status, &msg_tok); + + if (gss_kex_context == NULL) + gss_kex_context = ctxt; + else + ssh_gssapi_delete_ctx(&ctxt); + + /* Finally derive the keys and send them */ + if ((r = kex_derive_keys(ssh, hash, hashlen, shared_secret)) == 0) + r = kex_send_newkeys(ssh); + + /* If this was a rekey, then save out any delegated credentials we + * just exchanged. */ + if (options.gss_store_rekey) + ssh_gssapi_rekey_creds(); +out: + sshbuf_free(empty); + explicit_bzero(hash, sizeof(hash)); + DH_free(kex->dh); + kex->dh = NULL; + BN_clear_free(dh_client_pub); + sshbuf_free(shared_secret); + return r; +} +#endif /* defined(GSSAPI) && defined(WITH_OPENSSL) */ diff --git a/monitor.c b/monitor.c index 2ce89fe9..ebf76c7f 100644 --- a/monitor.c +++ b/monitor.c @@ -148,6 +148,8 @@ int mm_answer_gss_setup_ctx(struct ssh *, int, struct sshbuf *); int mm_answer_gss_accept_ctx(struct ssh *, int, struct sshbuf *); int mm_answer_gss_userok(struct ssh *, int, struct sshbuf *); int mm_answer_gss_checkmic(struct ssh *, int, struct sshbuf *); +int mm_answer_gss_sign(struct ssh *, int, struct sshbuf *); +int mm_answer_gss_updatecreds(struct ssh *, int, struct sshbuf *); #endif #ifdef SSH_AUDIT_EVENTS @@ -220,11 +222,18 @@ struct mon_table mon_dispatch_proto20[] = { {MONITOR_REQ_GSSSTEP, 0, mm_answer_gss_accept_ctx}, {MONITOR_REQ_GSSUSEROK, MON_ONCE|MON_AUTHDECIDE, mm_answer_gss_userok}, {MONITOR_REQ_GSSCHECKMIC, MON_ONCE, mm_answer_gss_checkmic}, + {MONITOR_REQ_GSSSIGN, MON_ONCE, mm_answer_gss_sign}, #endif {0, 0, NULL} }; struct mon_table mon_dispatch_postauth20[] = { +#ifdef GSSAPI + {MONITOR_REQ_GSSSETUP, 0, mm_answer_gss_setup_ctx}, + {MONITOR_REQ_GSSSTEP, 0, mm_answer_gss_accept_ctx}, + {MONITOR_REQ_GSSSIGN, 0, mm_answer_gss_sign}, + {MONITOR_REQ_GSSUPCREDS, 0, mm_answer_gss_updatecreds}, +#endif #ifdef WITH_OPENSSL {MONITOR_REQ_MODULI, 0, mm_answer_moduli}, #endif @@ -293,6 +302,10 @@ monitor_child_preauth(struct ssh *ssh, struct monitor *pmonitor) /* Permit requests for moduli and signatures */ monitor_permit(mon_dispatch, MONITOR_REQ_MODULI, 1); monitor_permit(mon_dispatch, MONITOR_REQ_SIGN, 1); +#ifdef GSSAPI + /* and for the GSSAPI key exchange */ + monitor_permit(mon_dispatch, MONITOR_REQ_GSSSETUP, 1); +#endif /* The first few requests do not require asynchronous access */ while (!authenticated) { @@ -376,8 +376,15 @@ monitor_child_preauth(struct ssh *ssh, s if (ent->flags & (MON_AUTHDECIDE|MON_ALOG)) { auth_log(ssh, authenticated, partial, auth_method, auth_submethod); - if (!partial && !authenticated) + if (!partial && !authenticated) { +#ifdef GSSAPI + /* If gssapi-with-mic failed, MONITOR_REQ_GSSCHECKMIC is disabled. + * We have to reenable it to try again for gssapi-keyex */ + if (strcmp(auth_method, "gssapi-with-mic") == 0 && options.gss_keyex) + monitor_permit(mon_dispatch, MONITOR_REQ_GSSCHECKMIC, 1); +#endif authctxt->failures++; + } if (authenticated || partial) { auth2_update_session_info(authctxt, auth_method, auth_submethod); @@ -406,6 +419,10 @@ monitor_child_postauth(struct ssh *ssh, struct monitor *pmonitor) monitor_permit(mon_dispatch, MONITOR_REQ_MODULI, 1); monitor_permit(mon_dispatch, MONITOR_REQ_SIGN, 1); monitor_permit(mon_dispatch, MONITOR_REQ_TERM, 1); +#ifdef GSSAPI + /* and for the GSSAPI key exchange */ + monitor_permit(mon_dispatch, MONITOR_REQ_GSSSETUP, 1); +#endif if (auth_opts->permit_pty_flag) { monitor_permit(mon_dispatch, MONITOR_REQ_PTY, 1); @@ -1713,6 +1730,17 @@ monitor_apply_keystate(struct ssh *ssh, struct monitor *pmonitor) # ifdef OPENSSL_HAS_ECC kex->kex[KEX_ECDH_SHA2] = kex_gen_server; # endif +# ifdef GSSAPI + if (options.gss_keyex) { + kex->kex[KEX_GSS_GRP1_SHA1] = kexgss_server; + kex->kex[KEX_GSS_GRP14_SHA1] = kexgss_server; + kex->kex[KEX_GSS_GRP14_SHA256] = kexgss_server; + kex->kex[KEX_GSS_GRP16_SHA512] = kexgss_server; + kex->kex[KEX_GSS_GEX_SHA1] = kexgssgex_server; + kex->kex[KEX_GSS_NISTP256_SHA256] = kexgss_server; + kex->kex[KEX_GSS_C25519_SHA256] = kexgss_server; + } +# endif #endif /* WITH_OPENSSL */ kex->kex[KEX_C25519_SHA256] = kex_gen_server; kex->kex[KEX_KEM_SNTRUP761X25519_SHA512] = kex_gen_server; @@ -1806,8 +1834,8 @@ mm_answer_gss_setup_ctx(struct ssh *ssh, int sock, struct sshbuf *m) u_char *p; int r; - if (!options.gss_authentication) - fatal_f("GSSAPI authentication not enabled"); + if (!options.gss_authentication && !options.gss_keyex) + fatal_f("GSSAPI not enabled"); if ((r = sshbuf_get_string(m, &p, &len)) != 0) fatal_fr(r, "parse"); @@ -1839,8 +1867,8 @@ mm_answer_gss_accept_ctx(struct ssh *ssh, int sock, struct sshbuf *m) OM_uint32 flags = 0; /* GSI needs this */ int r; - if (!options.gss_authentication) - fatal_f("GSSAPI authentication not enabled"); + if (!options.gss_authentication && !options.gss_keyex) + fatal_f("GSSAPI not enabled"); if ((r = ssh_gssapi_get_buffer_desc(m, &in)) != 0) fatal_fr(r, "ssh_gssapi_get_buffer_desc"); @@ -1860,6 +1888,7 @@ mm_answer_gss_accept_ctx(struct ssh *ssh, int sock, struct sshbuf *m) monitor_permit(mon_dispatch, MONITOR_REQ_GSSSTEP, 0); monitor_permit(mon_dispatch, MONITOR_REQ_GSSUSEROK, 1); monitor_permit(mon_dispatch, MONITOR_REQ_GSSCHECKMIC, 1); + monitor_permit(mon_dispatch, MONITOR_REQ_GSSSIGN, 1); } return (0); } @@ -1871,8 +1900,8 @@ mm_answer_gss_checkmic(struct ssh *ssh, int sock, struct sshbuf *m) OM_uint32 ret; int r; - if (!options.gss_authentication) - fatal_f("GSSAPI authentication not enabled"); + if (!options.gss_authentication && !options.gss_keyex) + fatal_f("GSSAPI not enabled"); if ((r = ssh_gssapi_get_buffer_desc(m, &gssbuf)) != 0 || (r = ssh_gssapi_get_buffer_desc(m, &mic)) != 0) @@ -1898,13 +1927,17 @@ mm_answer_gss_checkmic(struct ssh *ssh, int sock, struct sshbuf *m) int mm_answer_gss_userok(struct ssh *ssh, int sock, struct sshbuf *m) { - int r, authenticated; + int r, authenticated, kex; const char *displayname; - if (!options.gss_authentication) - fatal_f("GSSAPI authentication not enabled"); + if (!options.gss_authentication && !options.gss_keyex) + fatal_f("GSSAPI not enabled"); - authenticated = authctxt->valid && ssh_gssapi_userok(authctxt->user); + if ((r = sshbuf_get_u32(m, &kex)) != 0) + fatal_fr(r, "buffer error"); + + authenticated = authctxt->valid && + ssh_gssapi_userok(authctxt->user, authctxt->pw, kex); sshbuf_reset(m); if ((r = sshbuf_put_u32(m, authenticated)) != 0) @@ -1913,7 +1946,11 @@ mm_answer_gss_userok(struct ssh *ssh, int sock, struct sshbuf *m) debug3_f("sending result %d", authenticated); mm_request_send(sock, MONITOR_ANS_GSSUSEROK, m); - auth_method = "gssapi-with-mic"; + if (kex) { + auth_method = "gssapi-keyex"; + } else { + auth_method = "gssapi-with-mic"; + } if ((displayname = ssh_gssapi_displayname()) != NULL) auth2_record_info(authctxt, "%s", displayname); @@ -1921,5 +1958,84 @@ mm_answer_gss_userok(struct ssh *ssh, int sock, struct sshbuf *m) /* Monitor loop will terminate if authenticated */ return (authenticated); } + +int +mm_answer_gss_sign(struct ssh *ssh, int socket, struct sshbuf *m) +{ + gss_buffer_desc data; + gss_buffer_desc hash = GSS_C_EMPTY_BUFFER; + OM_uint32 major, minor; + size_t len; + u_char *p = NULL; + int r; + + if (!options.gss_authentication && !options.gss_keyex) + fatal_f("GSSAPI not enabled"); + + if ((r = sshbuf_get_string(m, &p, &len)) != 0) + fatal_fr(r, "buffer error"); + data.value = p; + data.length = len; + /* Lengths of SHA-1, SHA-256 and SHA-512 hashes that are used */ + if (data.length != 20 && data.length != 32 && data.length != 64) + fatal_f("data length incorrect: %d", (int) data.length); + + /* Save the session ID on the first time around */ + if (session_id2_len == 0) { + session_id2_len = data.length; + session_id2 = xmalloc(session_id2_len); + memcpy(session_id2, data.value, session_id2_len); + } + major = ssh_gssapi_sign(gsscontext, &data, &hash); + + free(data.value); + + sshbuf_reset(m); + + if ((r = sshbuf_put_u32(m, major)) != 0 || + (r = sshbuf_put_string(m, hash.value, hash.length)) != 0) + fatal_fr(r, "buffer error"); + + mm_request_send(socket, MONITOR_ANS_GSSSIGN, m); + + gss_release_buffer(&minor, &hash); + + /* Turn on getpwnam permissions */ + monitor_permit(mon_dispatch, MONITOR_REQ_PWNAM, 1); + + /* And credential updating, for when rekeying */ + monitor_permit(mon_dispatch, MONITOR_REQ_GSSUPCREDS, 1); + + return (0); +} + +int +mm_answer_gss_updatecreds(struct ssh *ssh, int socket, struct sshbuf *m) { + ssh_gssapi_ccache store; + int r, ok; + + if (!options.gss_authentication && !options.gss_keyex) + fatal_f("GSSAPI not enabled"); + + if ((r = sshbuf_get_string(m, (u_char **)&store.filename, NULL)) != 0 || + (r = sshbuf_get_string(m, (u_char **)&store.envvar, NULL)) != 0 || + (r = sshbuf_get_string(m, (u_char **)&store.envval, NULL)) != 0) + fatal_fr(r, "buffer error"); + + ok = ssh_gssapi_update_creds(&store); + + free(store.filename); + free(store.envvar); + free(store.envval); + + sshbuf_reset(m); + if ((r = sshbuf_put_u32(m, ok)) != 0) + fatal_fr(r, "buffer error"); + + mm_request_send(socket, MONITOR_ANS_GSSUPCREDS, m); + + return(0); +} + #endif /* GSSAPI */ diff --git a/monitor.h b/monitor.h index 683e5e07..2b1a2d59 100644 --- a/monitor.h +++ b/monitor.h @@ -63,6 +63,8 @@ enum monitor_reqtype { MONITOR_REQ_PAM_FREE_CTX = 110, MONITOR_ANS_PAM_FREE_CTX = 111, MONITOR_REQ_AUDIT_EVENT = 112, MONITOR_REQ_AUDIT_COMMAND = 113, + MONITOR_REQ_GSSSIGN = 150, MONITOR_ANS_GSSSIGN = 151, + MONITOR_REQ_GSSUPCREDS = 152, MONITOR_ANS_GSSUPCREDS = 153, }; struct ssh; diff --git a/monitor_wrap.c b/monitor_wrap.c index 001a8fa1..6edb509a 100644 --- a/monitor_wrap.c +++ b/monitor_wrap.c @@ -993,13 +993,15 @@ mm_ssh_gssapi_checkmic(Gssctxt *ctx, gss_buffer_t gssbuf, gss_buffer_t gssmic) } int -mm_ssh_gssapi_userok(char *user) +mm_ssh_gssapi_userok(char *user, struct passwd *pw, int kex) { struct sshbuf *m; int r, authenticated = 0; if ((m = sshbuf_new()) == NULL) fatal_f("sshbuf_new failed"); + if ((r = sshbuf_put_u32(m, kex)) != 0) + fatal_fr(r, "buffer error"); mm_request_send(pmonitor->m_recvfd, MONITOR_REQ_GSSUSEROK, m); mm_request_receive_expect(pmonitor->m_recvfd, @@ -1012,6 +1014,59 @@ mm_ssh_gssapi_userok(char *user) debug3_f("user %sauthenticated", authenticated ? "" : "not "); return (authenticated); } + +OM_uint32 +mm_ssh_gssapi_sign(Gssctxt *ctx, gss_buffer_desc *data, gss_buffer_desc *hash) +{ + struct sshbuf *m; + OM_uint32 major; + int r; + + if ((m = sshbuf_new()) == NULL) + fatal_f("sshbuf_new failed"); + if ((r = sshbuf_put_string(m, data->value, data->length)) != 0) + fatal_fr(r, "buffer error"); + + mm_request_send(pmonitor->m_recvfd, MONITOR_REQ_GSSSIGN, m); + mm_request_receive_expect(pmonitor->m_recvfd, MONITOR_ANS_GSSSIGN, m); + + if ((r = sshbuf_get_u32(m, &major)) != 0 || + (r = ssh_gssapi_get_buffer_desc(m, hash)) != 0) + fatal_fr(r, "buffer error"); + + sshbuf_free(m); + + return (major); +} + +int +mm_ssh_gssapi_update_creds(ssh_gssapi_ccache *store) +{ + struct sshbuf *m; + int r, ok; + + if ((m = sshbuf_new()) == NULL) + fatal_f("sshbuf_new failed"); + + if ((r = sshbuf_put_cstring(m, + store->filename ? store->filename : "")) != 0 || + (r = sshbuf_put_cstring(m, + store->envvar ? store->envvar : "")) != 0 || + (r = sshbuf_put_cstring(m, + store->envval ? store->envval : "")) != 0) + fatal_fr(r, "buffer error"); + + mm_request_send(pmonitor->m_recvfd, MONITOR_REQ_GSSUPCREDS, m); + mm_request_receive_expect(pmonitor->m_recvfd, MONITOR_ANS_GSSUPCREDS, m); + + if ((r = sshbuf_get_u32(m, &ok)) != 0) + fatal_fr(r, "buffer error"); + + sshbuf_free(m); + + return (ok); +} + #endif /* GSSAPI */ /* diff --git a/monitor_wrap.h b/monitor_wrap.h index 23ab096a..485590c1 100644 --- a/monitor_wrap.h +++ b/monitor_wrap.h @@ -64,8 +64,10 @@ int mm_sshkey_verify(const struct sshkey *, const u_char *, size_t, OM_uint32 mm_ssh_gssapi_server_ctx(Gssctxt **, gss_OID); OM_uint32 mm_ssh_gssapi_accept_ctx(Gssctxt *, gss_buffer_desc *, gss_buffer_desc *, OM_uint32 *); -int mm_ssh_gssapi_userok(char *user); +int mm_ssh_gssapi_userok(char *user, struct passwd *, int kex); OM_uint32 mm_ssh_gssapi_checkmic(Gssctxt *, gss_buffer_t, gss_buffer_t); +OM_uint32 mm_ssh_gssapi_sign(Gssctxt *, gss_buffer_t, gss_buffer_t); +int mm_ssh_gssapi_update_creds(ssh_gssapi_ccache *); #endif #ifdef USE_PAM diff -up a/readconf.c.gsskex b/readconf.c --- a/readconf.c.gsskex 2021-08-20 06:03:49.000000000 +0200 +++ b/readconf.c 2021-08-27 12:25:42.556421509 +0200 @@ -67,6 +67,7 @@ #include "uidswap.h" #include "myproposal.h" #include "digest.h" +#include "ssh-gss.h" #include "fips.h" @@ -161,6 +162,8 @@ typedef enum { oClearAllForwardings, oNoHostAuthenticationForLocalhost, oEnableSSHKeysign, oRekeyLimit, oVerifyHostKeyDNS, oConnectTimeout, oAddressFamily, oGssAuthentication, oGssDelegateCreds, + oGssTrustDns, oGssKeyEx, oGssClientIdentity, oGssRenewalRekey, + oGssServerIdentity, oGssKexAlgorithms, oServerAliveInterval, oServerAliveCountMax, oIdentitiesOnly, oSendEnv, oSetEnv, oControlPath, oControlMaster, oControlPersist, oHashKnownHosts, @@ -206,10 +209,22 @@ static struct { /* Sometimes-unsupported options */ #if defined(GSSAPI) { "gssapiauthentication", oGssAuthentication }, + { "gssapikeyexchange", oGssKeyEx }, { "gssapidelegatecredentials", oGssDelegateCreds }, + { "gssapitrustdns", oGssTrustDns }, + { "gssapiclientidentity", oGssClientIdentity }, + { "gssapiserveridentity", oGssServerIdentity }, + { "gssapirenewalforcesrekey", oGssRenewalRekey }, + { "gssapikexalgorithms", oGssKexAlgorithms }, # else { "gssapiauthentication", oUnsupported }, + { "gssapikeyexchange", oUnsupported }, { "gssapidelegatecredentials", oUnsupported }, + { "gssapitrustdns", oUnsupported }, + { "gssapiclientidentity", oUnsupported }, + { "gssapiserveridentity", oUnsupported }, + { "gssapirenewalforcesrekey", oUnsupported }, + { "gssapikexalgorithms", oUnsupported }, #endif #ifdef ENABLE_PKCS11 { "pkcs11provider", oPKCS11Provider }, @@ -1113,10 +1128,42 @@ parse_time: intptr = &options->gss_authentication; goto parse_flag; + case oGssKeyEx: + intptr = &options->gss_keyex; + goto parse_flag; + case oGssDelegateCreds: intptr = &options->gss_deleg_creds; goto parse_flag; + case oGssTrustDns: + intptr = &options->gss_trust_dns; + goto parse_flag; + + case oGssClientIdentity: + charptr = &options->gss_client_identity; + goto parse_string; + + case oGssServerIdentity: + charptr = &options->gss_server_identity; + goto parse_string; + + case oGssRenewalRekey: + intptr = &options->gss_renewal_rekey; + goto parse_flag; + + case oGssKexAlgorithms: + arg = argv_next(&ac, &av); + if (!arg || *arg == '\0') + fatal("%.200s line %d: Missing argument.", + filename, linenum); + if (!kex_gss_names_valid(arg)) + fatal("%.200s line %d: Bad GSSAPI KexAlgorithms '%s'.", + filename, linenum, arg ? arg : "<NONE>"); + if (*activep && options->gss_kex_algorithms == NULL) + options->gss_kex_algorithms = xstrdup(arg); + break; + case oBatchMode: intptr = &options->batch_mode; goto parse_flag; @@ -2306,7 +2353,13 @@ initialize_options(Options * options) options->fwd_opts.streamlocal_bind_unlink = -1; options->pubkey_authentication = -1; options->gss_authentication = -1; + options->gss_keyex = -1; options->gss_deleg_creds = -1; + options->gss_trust_dns = -1; + options->gss_renewal_rekey = -1; + options->gss_client_identity = NULL; + options->gss_server_identity = NULL; + options->gss_kex_algorithms = NULL; options->password_authentication = -1; options->kbd_interactive_authentication = -1; options->kbd_interactive_devices = NULL; @@ -2463,8 +2516,18 @@ fill_default_options(Options * options) options->pubkey_authentication = SSH_PUBKEY_AUTH_ALL; if (options->gss_authentication == -1) options->gss_authentication = 0; + if (options->gss_keyex == -1) + options->gss_keyex = 0; if (options->gss_deleg_creds == -1) options->gss_deleg_creds = 0; + if (options->gss_trust_dns == -1) + options->gss_trust_dns = 0; + if (options->gss_renewal_rekey == -1) + options->gss_renewal_rekey = 0; +#ifdef GSSAPI + if (options->gss_kex_algorithms == NULL) + options->gss_kex_algorithms = strdup(GSS_KEX_DEFAULT_KEX); +#endif if (options->password_authentication == -1) options->password_authentication = 1; if (options->kbd_interactive_authentication == -1) @@ -3246,7 +3309,14 @@ dump_client_config(Options *o, const cha dump_cfg_fmtint(oGatewayPorts, o->fwd_opts.gateway_ports); #ifdef GSSAPI dump_cfg_fmtint(oGssAuthentication, o->gss_authentication); + dump_cfg_fmtint(oGssKeyEx, o->gss_keyex); dump_cfg_fmtint(oGssDelegateCreds, o->gss_deleg_creds); + dump_cfg_fmtint(oGssTrustDns, o->gss_trust_dns); + dump_cfg_fmtint(oGssRenewalRekey, o->gss_renewal_rekey); + dump_cfg_string(oGssClientIdentity, o->gss_client_identity); + dump_cfg_string(oGssServerIdentity, o->gss_server_identity); + dump_cfg_string(oGssKexAlgorithms, o->gss_kex_algorithms ? + o->gss_kex_algorithms : GSS_KEX_DEFAULT_KEX); #endif /* GSSAPI */ dump_cfg_fmtint(oHashKnownHosts, o->hash_known_hosts); dump_cfg_fmtint(oHostbasedAuthentication, o->hostbased_authentication); diff -up a/readconf.h.gsskex b/readconf.h --- a/readconf.h.gsskex 2021-08-27 12:05:29.248142431 +0200 +++ b/readconf.h 2021-08-27 12:22:19.270679852 +0200 @@ -39,7 +39,13 @@ typedef struct { int pubkey_authentication; /* Try ssh2 pubkey authentication. */ int hostbased_authentication; /* ssh2's rhosts_rsa */ int gss_authentication; /* Try GSS authentication */ + int gss_keyex; /* Try GSS key exchange */ int gss_deleg_creds; /* Delegate GSS credentials */ + int gss_trust_dns; /* Trust DNS for GSS canonicalization */ + int gss_renewal_rekey; /* Credential renewal forces rekey */ + char *gss_client_identity; /* Principal to initiate GSSAPI with */ + char *gss_server_identity; /* GSSAPI target principal */ + char *gss_kex_algorithms; /* GSSAPI kex methods to be offered by client. */ int password_authentication; /* Try password * authentication. */ int kbd_interactive_authentication; /* Try keyboard-interactive auth. */ diff -up a/servconf.c.gsskex b/servconf.c --- a/servconf.c.gsskex 2021-08-20 06:03:49.000000000 +0200 +++ b/servconf.c 2021-08-27 12:28:15.887735189 +0200 @@ -70,6 +70,7 @@ #include "auth.h" #include "myproposal.h" #include "digest.h" +#include "ssh-gss.h" #include "fips.h" #if !defined(SSHD_PAM_SERVICE) @@ -136,8 +137,11 @@ initialize_server_options(ServerOptions options->kerberos_ticket_cleanup = -1; options->kerberos_get_afs_token = -1; options->gss_authentication=-1; + options->gss_keyex = -1; options->gss_cleanup_creds = -1; options->gss_strict_acceptor = -1; + options->gss_store_rekey = -1; + options->gss_kex_algorithms = NULL; options->password_authentication = -1; options->kbd_interactive_authentication = -1; options->permit_empty_passwd = -1; @@ -356,10 +360,18 @@ fill_default_server_options(ServerOption options->kerberos_get_afs_token = 0; if (options->gss_authentication == -1) options->gss_authentication = 0; + if (options->gss_keyex == -1) + options->gss_keyex = 0; if (options->gss_cleanup_creds == -1) options->gss_cleanup_creds = 1; if (options->gss_strict_acceptor == -1) options->gss_strict_acceptor = 1; + if (options->gss_store_rekey == -1) + options->gss_store_rekey = 0; +#ifdef GSSAPI + if (options->gss_kex_algorithms == NULL) + options->gss_kex_algorithms = strdup(GSS_KEX_DEFAULT_KEX); +#endif if (options->password_authentication == -1) options->password_authentication = 1; if (options->kbd_interactive_authentication == -1) @@ -506,6 +518,7 @@ typedef enum { sPerSourcePenalties, sPerSourcePenaltyExemptList, sClientAliveInterval, sClientAliveCountMax, sAuthorizedKeysFile, sGssAuthentication, sGssCleanupCreds, sGssStrictAcceptor, + sGssKeyEx, sGssKexAlgorithms, sGssStoreRekey, sAcceptEnv, sSetEnv, sPermitTunnel, sMatch, sPermitOpen, sPermitListen, sForceCommand, sChrootDirectory, sUsePrivilegeSeparation, sAllowAgentForwarding, @@ -587,12 +600,22 @@ static struct { #ifdef GSSAPI { "gssapiauthentication", sGssAuthentication, SSHCFG_ALL }, { "gssapicleanupcredentials", sGssCleanupCreds, SSHCFG_GLOBAL }, + { "gssapicleanupcreds", sGssCleanupCreds, SSHCFG_GLOBAL }, { "gssapistrictacceptorcheck", sGssStrictAcceptor, SSHCFG_GLOBAL }, + { "gssapikeyexchange", sGssKeyEx, SSHCFG_GLOBAL }, + { "gssapistorecredentialsonrekey", sGssStoreRekey, SSHCFG_GLOBAL }, + { "gssapikexalgorithms", sGssKexAlgorithms, SSHCFG_GLOBAL }, #else { "gssapiauthentication", sUnsupported, SSHCFG_ALL }, { "gssapicleanupcredentials", sUnsupported, SSHCFG_GLOBAL }, + { "gssapicleanupcreds", sUnsupported, SSHCFG_GLOBAL }, { "gssapistrictacceptorcheck", sUnsupported, SSHCFG_GLOBAL }, + { "gssapikeyexchange", sUnsupported, SSHCFG_GLOBAL }, + { "gssapistorecredentialsonrekey", sUnsupported, SSHCFG_GLOBAL }, + { "gssapikexalgorithms", sUnsupported, SSHCFG_GLOBAL }, #endif + { "gssusesessionccache", sUnsupported, SSHCFG_GLOBAL }, + { "gssapiusesessioncredcache", sUnsupported, SSHCFG_GLOBAL }, { "passwordauthentication", sPasswordAuthentication, SSHCFG_ALL }, { "kbdinteractiveauthentication", sKbdInteractiveAuthentication, SSHCFG_ALL }, { "challengeresponseauthentication", sKbdInteractiveAuthentication, SSHCFG_ALL }, /* alias */ @@ -1576,6 +1599,10 @@ process_server_config_line_depth(ServerO intptr = &options->gss_authentication; goto parse_flag; + case sGssKeyEx: + intptr = &options->gss_keyex; + goto parse_flag; + case sGssCleanupCreds: intptr = &options->gss_cleanup_creds; goto parse_flag; @@ -1584,6 +1611,22 @@ process_server_config_line_depth(ServerO intptr = &options->gss_strict_acceptor; goto parse_flag; + case sGssStoreRekey: + intptr = &options->gss_store_rekey; + goto parse_flag; + + case sGssKexAlgorithms: + arg = argv_next(&ac, &av); + if (!arg || *arg == '\0') + fatal("%.200s line %d: Missing argument.", + filename, linenum); + if (!kex_gss_names_valid(arg)) + fatal("%.200s line %d: Bad GSSAPI KexAlgorithms '%s'.", + filename, linenum, arg ? arg : "<NONE>"); + if (*activep && options->gss_kex_algorithms == NULL) + options->gss_kex_algorithms = xstrdup(arg); + break; + case sPasswordAuthentication: intptr = &options->password_authentication; goto parse_flag; @@ -2892,6 +2935,10 @@ dump_config(ServerOptions *o) #ifdef GSSAPI dump_cfg_fmtint(sGssAuthentication, o->gss_authentication); dump_cfg_fmtint(sGssCleanupCreds, o->gss_cleanup_creds); + dump_cfg_fmtint(sGssKeyEx, o->gss_keyex); + dump_cfg_fmtint(sGssStrictAcceptor, o->gss_strict_acceptor); + dump_cfg_fmtint(sGssStoreRekey, o->gss_store_rekey); + dump_cfg_string(sGssKexAlgorithms, o->gss_kex_algorithms); #endif dump_cfg_fmtint(sPasswordAuthentication, o->password_authentication); dump_cfg_fmtint(sKbdInteractiveAuthentication, diff --git a/servconf.h b/servconf.h index 4202a2d0..3f47ea25 100644 --- a/servconf.h +++ b/servconf.h @@ -132,8 +132,11 @@ typedef struct { int kerberos_get_afs_token; /* If true, try to get AFS token if * authenticated with Kerberos. */ int gss_authentication; /* If true, permit GSSAPI authentication */ + int gss_keyex; /* If true, permit GSSAPI key exchange */ int gss_cleanup_creds; /* If true, destroy cred cache on logout */ int gss_strict_acceptor; /* If true, restrict the GSSAPI acceptor name */ + int gss_store_rekey; + char *gss_kex_algorithms; /* GSSAPI kex methods to be offered by client. */ int password_authentication; /* If true, permit password * authentication. */ int kbd_interactive_authentication; /* If true, permit */ diff --git a/session.c b/session.c index 8c0e54f7..06a33442 100644 --- a/session.c +++ b/session.c @@ -2678,13 +2678,19 @@ do_cleanup(struct ssh *ssh, Authctxt *authctxt) #ifdef KRB5 if (options.kerberos_ticket_cleanup && - authctxt->krb5_ctx) + authctxt->krb5_ctx) { + temporarily_use_uid(authctxt->pw); krb5_cleanup_proc(authctxt); + restore_uid(); + } #endif #ifdef GSSAPI - if (options.gss_cleanup_creds) + if (options.gss_cleanup_creds) { + temporarily_use_uid(authctxt->pw); ssh_gssapi_cleanup_creds(); + restore_uid(); + } #endif /* remove agent socket */ diff --git a/ssh-gss.h b/ssh-gss.h index 36180d07..70dd3665 100644 --- a/ssh-gss.h +++ b/ssh-gss.h @@ -61,10 +61,34 @@ #define SSH_GSS_OIDTYPE 0x06 +#define SSH2_MSG_KEXGSS_INIT 30 +#define SSH2_MSG_KEXGSS_CONTINUE 31 +#define SSH2_MSG_KEXGSS_COMPLETE 32 +#define SSH2_MSG_KEXGSS_HOSTKEY 33 +#define SSH2_MSG_KEXGSS_ERROR 34 +#define SSH2_MSG_KEXGSS_GROUPREQ 40 +#define SSH2_MSG_KEXGSS_GROUP 41 +#define KEX_GSS_GRP1_SHA1_ID "gss-group1-sha1-" +#define KEX_GSS_GRP14_SHA1_ID "gss-group14-sha1-" +#define KEX_GSS_GRP14_SHA256_ID "gss-group14-sha256-" +#define KEX_GSS_GRP16_SHA512_ID "gss-group16-sha512-" +#define KEX_GSS_GEX_SHA1_ID "gss-gex-sha1-" +#define KEX_GSS_NISTP256_SHA256_ID "gss-nistp256-sha256-" +#define KEX_GSS_C25519_SHA256_ID "gss-curve25519-sha256-" + +#define GSS_KEX_DEFAULT_KEX \ + KEX_GSS_GRP14_SHA256_ID "," \ + KEX_GSS_GRP16_SHA512_ID "," \ + KEX_GSS_NISTP256_SHA256_ID "," \ + KEX_GSS_C25519_SHA256_ID "," \ + KEX_GSS_GRP14_SHA1_ID "," \ + KEX_GSS_GEX_SHA1_ID + typedef struct { char *filename; char *envvar; char *envval; + struct passwd *owner; void *data; } ssh_gssapi_ccache; @@ -72,8 +92,11 @@ typedef struct { gss_buffer_desc displayname; gss_buffer_desc exportedname; gss_cred_id_t creds; + gss_name_t name; struct ssh_gssapi_mech_struct *mech; ssh_gssapi_ccache store; + int used; + int updated; } ssh_gssapi_client; typedef struct ssh_gssapi_mech_struct { @@ -84,6 +107,7 @@ typedef struct ssh_gssapi_mech_struct { int (*userok) (ssh_gssapi_client *, char *); int (*localname) (ssh_gssapi_client *, char **); void (*storecreds) (ssh_gssapi_client *); + int (*updatecreds) (ssh_gssapi_ccache *, ssh_gssapi_client *); } ssh_gssapi_mech; typedef struct { @@ -94,10 +118,11 @@ typedef struct { gss_OID oid; /* client */ gss_cred_id_t creds; /* server */ gss_name_t client; /* server */ - gss_cred_id_t client_creds; /* server */ + gss_cred_id_t client_creds; /* both */ } Gssctxt; extern ssh_gssapi_mech *supported_mechs[]; +extern Gssctxt *gss_kex_context; int ssh_gssapi_check_oid(Gssctxt *, void *, size_t); void ssh_gssapi_set_oid_data(Gssctxt *, void *, size_t); @@ -109,6 +134,7 @@ OM_uint32 ssh_gssapi_test_oid_supported(OM_uint32 *, gss_OID, int *); struct sshbuf; int ssh_gssapi_get_buffer_desc(struct sshbuf *, gss_buffer_desc *); +int ssh_gssapi_sshpkt_get_buffer_desc(struct ssh *, gss_buffer_desc *); OM_uint32 ssh_gssapi_import_name(Gssctxt *, const char *); OM_uint32 ssh_gssapi_init_ctx(Gssctxt *, int, @@ -123,17 +149,33 @@ void ssh_gssapi_delete_ctx(Gssctxt **); OM_uint32 ssh_gssapi_sign(Gssctxt *, gss_buffer_t, gss_buffer_t); void ssh_gssapi_buildmic(struct sshbuf *, const char *, const char *, const char *, const struct sshbuf *); -int ssh_gssapi_check_mechanism(Gssctxt **, gss_OID, const char *); +int ssh_gssapi_check_mechanism(Gssctxt **, gss_OID, const char *, const char *); +OM_uint32 ssh_gssapi_client_identity(Gssctxt *, const char *); +int ssh_gssapi_credentials_updated(Gssctxt *); /* In the server */ +typedef int ssh_gssapi_check_fn(Gssctxt **, gss_OID, const char *, + const char *); +char *ssh_gssapi_client_mechanisms(const char *, const char *, const char *); +char *ssh_gssapi_kex_mechs(gss_OID_set, ssh_gssapi_check_fn *, const char *, + const char *, const char *); +gss_OID ssh_gssapi_id_kex(Gssctxt *, char *, int); +int ssh_gssapi_server_check_mech(Gssctxt **,gss_OID, const char *, + const char *); OM_uint32 ssh_gssapi_server_ctx(Gssctxt **, gss_OID); -int ssh_gssapi_userok(char *name); +int ssh_gssapi_userok(char *name, struct passwd *, int kex); OM_uint32 ssh_gssapi_checkmic(Gssctxt *, gss_buffer_t, gss_buffer_t); void ssh_gssapi_do_child(char ***, u_int *); void ssh_gssapi_cleanup_creds(void); void ssh_gssapi_storecreds(void); const char *ssh_gssapi_displayname(void); +char *ssh_gssapi_server_mechanisms(void); +int ssh_gssapi_oid_table_ok(void); + +int ssh_gssapi_update_creds(ssh_gssapi_ccache *store); +void ssh_gssapi_rekey_creds(void); + #endif /* GSSAPI */ #endif /* _SSH_GSS_H */ diff --git a/ssh.1 b/ssh.1 index 60de6087..db5c65bc 100644 --- a/ssh.1 +++ b/ssh.1 @@ -503,7 +503,13 @@ For full details of the options listed below, and their possible values, see .It GatewayPorts .It GlobalKnownHostsFile .It GSSAPIAuthentication +.It GSSAPIKeyExchange +.It GSSAPIClientIdentity .It GSSAPIDelegateCredentials +.It GSSAPIKexAlgorithms +.It GSSAPIRenewalForcesRekey +.It GSSAPIServerIdentity +.It GSSAPITrustDns .It HashKnownHosts .It Host .It HostbasedAcceptedAlgorithms @@ -624,6 +624,8 @@ (supported message integrity codes), .Ar kex (key exchange algorithms), +.Ar kex-gss +(GSSAPI key exchange algorithms), .Ar key (key types), .Ar key-ca-sign diff --git a/ssh.c b/ssh.c index 15aee569..110cf9c1 100644 --- a/ssh.c +++ b/ssh.c @@ -747,6 +747,8 @@ main(int ac, char **av) else if (strcmp(optarg, "kex") == 0 || strcasecmp(optarg, "KexAlgorithms") == 0) cp = kex_alg_list('\n'); + else if (strcmp(optarg, "kex-gss") == 0) + cp = kex_gss_alg_list('\n'); else if (strcmp(optarg, "key") == 0) cp = sshkey_alg_list(0, 0, 0, '\n'); else if (strcmp(optarg, "key-cert") == 0) @@ -772,8 +774,8 @@ main(int ac, char **av) } else if (strcmp(optarg, "help") == 0) { cp = xstrdup( "cipher\ncipher-auth\ncompression\nkex\n" - "key\nkey-cert\nkey-plain\nkey-sig\nmac\n" - "protocol-version\nsig"); + "kex-gss\nkey\nkey-cert\nkey-plain\n" + "key-sig\nmac\nprotocol-version\nsig"); } if (cp == NULL) fatal("Unsupported query \"%s\"", optarg); diff --git a/ssh_config b/ssh_config index 5e8ef548..1ff999b6 100644 --- a/ssh_config +++ b/ssh_config @@ -24,6 +24,8 @@ # HostbasedAuthentication no # GSSAPIAuthentication no # GSSAPIDelegateCredentials no +# GSSAPIKeyExchange no +# GSSAPITrustDNS no # BatchMode no # CheckHostIP no # AddressFamily any diff --git a/ssh_config.5 b/ssh_config.5 index 06a32d31..3f490697 100644 --- a/ssh_config.5 +++ b/ssh_config.5 @@ -766,10 +766,68 @@ The default is Specifies whether user authentication based on GSSAPI is allowed. The default is .Cm no . +.It Cm GSSAPIClientIdentity +If set, specifies the GSSAPI client identity that ssh should use when +connecting to the server. The default is unset, which means that the default +identity will be used. .It Cm GSSAPIDelegateCredentials Forward (delegate) credentials to the server. The default is .Cm no . +.It Cm GSSAPIKeyExchange +Specifies whether key exchange based on GSSAPI may be used. When using +GSSAPI key exchange the server need not have a host key. +The default is +.Dq no . +.It Cm GSSAPIRenewalForcesRekey +If set to +.Dq yes +then renewal of the client's GSSAPI credentials will force the rekeying of the +ssh connection. With a compatible server, this will delegate the renewed +credentials to a session on the server. +.Pp +Checks are made to ensure that credentials are only propagated when the new +credentials match the old ones on the originating client and where the +receiving server still has the old set in its cache. +.Pp +The default is +.Dq no . +.Pp +For this to work +.Cm GSSAPIKeyExchange +needs to be enabled in the server and also used by the client. +.It Cm GSSAPIServerIdentity +If set, specifies the GSSAPI server identity that ssh should expect when +connecting to the server. The default is unset, which means that the +expected GSSAPI server identity will be determined from the target +hostname. +.It Cm GSSAPITrustDns +Set to +.Dq yes +to indicate that the DNS is trusted to securely canonicalize +the name of the host being connected to. If +.Dq no , +the hostname entered on the +command line will be passed untouched to the GSSAPI library. +The default is +.Dq no . +.It Cm GSSAPIKexAlgorithms +The list of key exchange algorithms that are offered for GSSAPI +key exchange. Possible values are +.Bd -literal -offset 3n +gss-gex-sha1-, +gss-group1-sha1-, +gss-group14-sha1-, +gss-group14-sha256-, +gss-group16-sha512-, +gss-nistp256-sha256-, +gss-curve25519-sha256- +.Ed +.Pp +The default is +.Dq gss-group14-sha256-,gss-group16-sha512-,gss-nistp256-sha256-, +gss-curve25519-sha256-,gss-group14-sha1-,gss-gex-sha1- . +This option only applies to connections using GSSAPI. .It Cm HashKnownHosts Indicates that .Xr ssh 1 diff --git a/sshconnect2.c b/sshconnect2.c index af00fb30..03bc87eb 100644 --- a/sshconnect2.c +++ b/sshconnect2.c @@ -163,6 +161,11 @@ ssh_kex2(struct ssh *ssh, char *host, struct sockaddr *hostaddr, u_short port) char *all_key, *hkalgs = NULL; int r, use_known_hosts_order = 0; +#if defined(GSSAPI) && defined(WITH_OPENSSL) + char *orig = NULL, *gss = NULL; + char *gss_host = NULL; +#endif + xxx_host = host; xxx_hostaddr = hostaddr; xxx_conn_info = cinfo; @@ -206,6 +209,42 @@ ssh_kex2(struct ssh *ssh, char *host, struct sockaddr *hostaddr, u_short port) options.kex_algorithms, options.ciphers, options.macs, compression_alg_list(options.compression), hkalgs ? hkalgs : options.hostkeyalgorithms); + +#if defined(GSSAPI) && defined(WITH_OPENSSL) + if (options.gss_keyex) { + /* Add the GSSAPI mechanisms currently supported on this + * client to the key exchange algorithm proposal */ + orig = myproposal[PROPOSAL_KEX_ALGS]; + + if (options.gss_server_identity) { + gss_host = xstrdup(options.gss_server_identity); + } else if (options.gss_trust_dns) { + gss_host = remote_hostname(ssh); + /* Fall back to specified host if we are using proxy command + * and can not use DNS on that socket */ + if (strcmp(gss_host, "UNKNOWN") == 0) { + free(gss_host); + gss_host = xstrdup(host); + } + } else { + gss_host = xstrdup(host); + } + + gss = ssh_gssapi_client_mechanisms(gss_host, + options.gss_client_identity, options.gss_kex_algorithms); + if (gss) { + debug("Offering GSSAPI proposal: %s", gss); + xasprintf(&myproposal[PROPOSAL_KEX_ALGS], + "%s,%s", gss, orig); + + /* If we've got GSSAPI algorithms, then we also support the + * 'null' hostkey, as a last resort */ + orig = myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS]; + xasprintf(&myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS], + "%s,null", orig); + } + } +#endif free(hkalgs); @@ -224,15 +256,45 @@ ssh_kex2(struct ssh *ssh, char *host, struct sockaddr *hostaddr, u_short port) # ifdef OPENSSL_HAS_ECC ssh->kex->kex[KEX_ECDH_SHA2] = kex_gen_client; # endif -#endif +# ifdef GSSAPI + if (options.gss_keyex) { + ssh->kex->kex[KEX_GSS_GRP1_SHA1] = kexgss_client; + ssh->kex->kex[KEX_GSS_GRP14_SHA1] = kexgss_client; + ssh->kex->kex[KEX_GSS_GRP14_SHA256] = kexgss_client; + ssh->kex->kex[KEX_GSS_GRP16_SHA512] = kexgss_client; + ssh->kex->kex[KEX_GSS_GEX_SHA1] = kexgssgex_client; + ssh->kex->kex[KEX_GSS_NISTP256_SHA256] = kexgss_client; + ssh->kex->kex[KEX_GSS_C25519_SHA256] = kexgss_client; + } +# endif +#endif /* WITH_OPENSSL */ ssh->kex->kex[KEX_C25519_SHA256] = kex_gen_client; ssh->kex->kex[KEX_KEM_SNTRUP761X25519_SHA512] = kex_gen_client; ssh->kex->kex[KEX_KEM_MLKEM768X25519_SHA256] = kex_gen_client; ssh->kex->verify_host_key=&verify_host_key_callback; +#if defined(GSSAPI) && defined(WITH_OPENSSL) + if (options.gss_keyex) { + ssh->kex->gss_deleg_creds = options.gss_deleg_creds; + ssh->kex->gss_trust_dns = options.gss_trust_dns; + ssh->kex->gss_client = options.gss_client_identity; + ssh->kex->gss_host = gss_host; + } +#endif + ssh_dispatch_run_fatal(ssh, DISPATCH_BLOCK, &ssh->kex->done); kex_proposal_free_entries(myproposal); +#if defined(GSSAPI) && defined(WITH_OPENSSL) + /* repair myproposal after it was crumpled by the */ + /* ext-info removal above */ + if (gss) { + orig = myproposal[PROPOSAL_KEX_ALGS]; + xasprintf(&myproposal[PROPOSAL_KEX_ALGS], + "%s,%s", gss, orig); + free(gss); + } +#endif #ifdef DEBUG_KEXDH /* send 1st encrypted/maced/compressed message */ if ((r = sshpkt_start(ssh, SSH2_MSG_IGNORE)) != 0 || @@ -330,6 +392,7 @@ static int input_gssapi_response(int type, u_int32_t, struct ssh *); static int input_gssapi_token(int type, u_int32_t, struct ssh *); static int input_gssapi_error(int, u_int32_t, struct ssh *); static int input_gssapi_errtok(int, u_int32_t, struct ssh *); +static int userauth_gsskeyex(struct ssh *); #endif void userauth(struct ssh *, char *); @@ -346,6 +409,11 @@ static char *authmethods_get(void); Authmethod authmethods[] = { #ifdef GSSAPI + {"gssapi-keyex", + userauth_gsskeyex, + NULL, + &options.gss_keyex, + NULL}, {"gssapi-with-mic", userauth_gssapi, userauth_gssapi_cleanup, @@ -716,12 +784,32 @@ userauth_gssapi(struct ssh *ssh) OM_uint32 min; int r, ok = 0; gss_OID mech = NULL; + char *gss_host = NULL; + + if (options.gss_server_identity) { + gss_host = xstrdup(options.gss_server_identity); + } else if (options.gss_trust_dns) { + gss_host = remote_hostname(ssh); + /* Fall back to specified host if we are using proxy command + * and can not use DNS on that socket */ + if (strcmp(gss_host, "UNKNOWN") == 0) { + free(gss_host); + gss_host = xstrdup(authctxt->host); + } + } else { + gss_host = xstrdup(authctxt->host); + } /* Try one GSSAPI method at a time, rather than sending them all at * once. */ if (authctxt->gss_supported_mechs == NULL) - gss_indicate_mechs(&min, &authctxt->gss_supported_mechs); + if (GSS_ERROR(gss_indicate_mechs(&min, + &authctxt->gss_supported_mechs))) { + authctxt->gss_supported_mechs = NULL; + free(gss_host); + return 0; + } /* Check to see whether the mechanism is usable before we offer it */ while (authctxt->mech_tried < authctxt->gss_supported_mechs->count && @@ -730,13 +811,15 @@ userauth_gssapi(struct ssh *ssh) elements[authctxt->mech_tried]; /* My DER encoding requires length<128 */ if (mech->length < 128 && ssh_gssapi_check_mechanism(&gssctxt, - mech, authctxt->host)) { + mech, gss_host, options.gss_client_identity)) { ok = 1; /* Mechanism works */ } else { authctxt->mech_tried++; } } + free(gss_host); + if (!ok || mech == NULL) return 0; @@ -976,6 +1059,55 @@ input_gssapi_error(int type, u_int32_t plen, struct ssh *ssh) free(lang); return r; } + +int +userauth_gsskeyex(struct ssh *ssh) +{ + struct sshbuf *b = NULL; + Authctxt *authctxt = ssh->authctxt; + gss_buffer_desc gssbuf; + gss_buffer_desc mic = GSS_C_EMPTY_BUFFER; + OM_uint32 ms; + int r; + + static int attempt = 0; + if (attempt++ >= 1) + return (0); + + if (gss_kex_context == NULL) { + debug("No valid Key exchange context"); + return (0); + } + + if ((b = sshbuf_new()) == NULL) + fatal_f("sshbuf_new failed"); + + ssh_gssapi_buildmic(b, authctxt->server_user, authctxt->service, + "gssapi-keyex", ssh->kex->session_id); + + if ((gssbuf.value = sshbuf_mutable_ptr(b)) == NULL) + fatal_f("sshbuf_mutable_ptr failed"); + gssbuf.length = sshbuf_len(b); + + if (GSS_ERROR(ssh_gssapi_sign(gss_kex_context, &gssbuf, &mic))) { + sshbuf_free(b); + return (0); + } + + if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 || + (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 || + (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 || + (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 || + (r = sshpkt_put_string(ssh, mic.value, mic.length)) != 0 || + (r = sshpkt_send(ssh)) != 0) + fatal_fr(r, "parsing"); + + sshbuf_free(b); + gss_release_buffer(&ms, &mic); + + return (1); +} + #endif /* GSSAPI */ static int diff --git a/sshd.c b/sshd.c index 60b2aaf7..d92f03aa 100644 --- a/sshd.c +++ b/sshd.c @@ -1852,7 +1852,8 @@ main(int ac, char **av) free(fp); } accumulate_host_timing_secret(cfg, NULL); - if (!sensitive_data.have_ssh2_key) { + /* The GSSAPI key exchange can run without a host key */ + if (!sensitive_data.have_ssh2_key && !options.gss_keyex) { logit("sshd: no hostkeys available -- exiting."); exit(1); } diff --git a/sshd-session.c b/sshd-session.c index 60b2aaf7..d92f03aa 100644 --- a/sshd-session.c +++ b/sshd-session.c @@ -817,8 +817,8 @@ notify_hostkeys(struct ssh *ssh) } debug3_f("sent %u hostkeys", nkeys); if (nkeys == 0) - fatal_f("no hostkeys"); - if ((r = sshpkt_send(ssh)) != 0) + debug3_f("no hostkeys"); + else if ((r = sshpkt_send(ssh)) != 0) sshpkt_fatal(ssh, r, "%s: send", __func__); sshbuf_free(buf); } @@ -2347,6 +2348,48 @@ do_ssh2_kex(struct ssh *ssh) free(hkalgs); +#if defined(GSSAPI) && defined(WITH_OPENSSL) + { + char *orig; + char *gss = NULL; + char *newstr = NULL; + orig = myproposal[PROPOSAL_KEX_ALGS]; + + /* + * If we don't have a host key, then there's no point advertising + * the other key exchange algorithms + */ + + if (strlen(myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS]) == 0) + orig = NULL; + + if (options.gss_keyex) + gss = ssh_gssapi_server_mechanisms(); + else + gss = NULL; + + if (gss && orig) + xasprintf(&newstr, "%s,%s", gss, orig); + else if (gss) + newstr = gss; + else if (orig) + newstr = orig; + + /* + * If we've got GSSAPI mechanisms, then we've got the 'null' host + * key alg, but we can't tell people about it unless its the only + * host key algorithm we support + */ + if (gss && (strlen(myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS])) == 0) + myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = "null"; + + if (newstr) + myproposal[PROPOSAL_KEX_ALGS] = newstr; + else + fatal("No supported key exchange algorithms"); + } +#endif + /* start key exchange */ if ((r = kex_setup(ssh, myproposal)) != 0) fatal_r(r, "kex_setup"); @@ -2362,7 +2405,18 @@ do_ssh2_kex(struct ssh *ssh) #ifdef OPENSSL_HAS_ECC kex->kex[KEX_ECDH_SHA2] = kex_gen_server; #endif -#endif +# ifdef GSSAPI + if (options.gss_keyex) { + kex->kex[KEX_GSS_GRP1_SHA1] = kexgss_server; + kex->kex[KEX_GSS_GRP14_SHA1] = kexgss_server; + kex->kex[KEX_GSS_GRP14_SHA256] = kexgss_server; + kex->kex[KEX_GSS_GRP16_SHA512] = kexgss_server; + kex->kex[KEX_GSS_GEX_SHA1] = kexgssgex_server; + kex->kex[KEX_GSS_NISTP256_SHA256] = kexgss_server; + kex->kex[KEX_GSS_C25519_SHA256] = kexgss_server; + } +# endif +#endif /* WITH_OPENSSL */ kex->kex[KEX_C25519_SHA256] = kex_gen_server; kex->kex[KEX_KEM_SNTRUP761X25519_SHA512] = kex_gen_server; kex->kex[KEX_KEM_MLKEM768X25519_SHA256] = kex_gen_server; diff --git a/sshd_config b/sshd_config index 19b7c91a..2c48105f 100644 --- a/sshd_config +++ b/sshd_config @@ -69,6 +69,8 @@ AuthorizedKeysFile .ssh/authorized_keys # GSSAPI options #GSSAPIAuthentication no #GSSAPICleanupCredentials yes +#GSSAPIStrictAcceptorCheck yes +#GSSAPIKeyExchange no # Set this to 'yes' to enable PAM authentication, account processing, # and session processing. If this is enabled, PAM authentication will diff --git a/sshd_config.5 b/sshd_config.5 index 70ccea44..f6b41a2f 100644 --- a/sshd_config.5 +++ b/sshd_config.5 @@ -646,6 +646,11 @@ Specifies whether to automatically destroy the user's credentials cache on logout. The default is .Cm yes . +.It Cm GSSAPIKeyExchange +Specifies whether key exchange based on GSSAPI is allowed. GSSAPI key exchange +doesn't rely on ssh keys to verify host identity. +The default is +.Cm no . .It Cm GSSAPIStrictAcceptorCheck Determines whether to be strict about the identity of the GSSAPI acceptor a client authenticates against. @@ -660,6 +665,32 @@ machine's default store. This facility is provided to assist with operation on multi homed machines. The default is .Cm yes . +.It Cm GSSAPIStoreCredentialsOnRekey +Controls whether the user's GSSAPI credentials should be updated following a +successful connection rekeying. This option can be used to accepted renewed +or updated credentials from a compatible client. The default is +.Dq no . +.Pp +For this to work +.Cm GSSAPIKeyExchange +needs to be enabled in the server and also used by the client. +.It Cm GSSAPIKexAlgorithms +The list of key exchange algorithms that are accepted by GSSAPI +key exchange. Possible values are +.Bd -literal -offset 3n +gss-gex-sha1-, +gss-group1-sha1-, +gss-group14-sha1-, +gss-group14-sha256-, +gss-group16-sha512-, +gss-nistp256-sha256-, +gss-curve25519-sha256- +.Ed +.Pp +The default is +.Dq gss-group14-sha256-,gss-group16-sha512-,gss-nistp256-sha256-, +gss-curve25519-sha256-,gss-group14-sha1-,gss-gex-sha1- . +This option only applies to connections using GSSAPI. .It Cm HostbasedAcceptedAlgorithms Specifies the signature algorithms that will be accepted for hostbased authentication as a list of comma-separated patterns. diff --git a/sshkey.c b/sshkey.c index 57995ee6..fd5b7724 100644 --- a/sshkey.c +++ b/sshkey.c @@ -127,6 +127,75 @@ static const struct keytype keytypes[] = { extern const struct sshkey_impl sshkey_xmss_impl; extern const struct sshkey_impl sshkey_xmss_cert_impl; #endif + +static int ssh_gss_equal(const struct sshkey *, const struct sshkey *) +{ + return SSH_ERR_FEATURE_UNSUPPORTED; +} + +static int ssh_gss_serialize_public(const struct sshkey *, struct sshbuf *, + enum sshkey_serialize_rep) +{ + return SSH_ERR_FEATURE_UNSUPPORTED; +} + +static int ssh_gss_deserialize_public(const char *, struct sshbuf *, + struct sshkey *) +{ + return SSH_ERR_FEATURE_UNSUPPORTED; +} + +static int ssh_gss_serialize_private(const struct sshkey *, struct sshbuf *, + enum sshkey_serialize_rep) +{ + return SSH_ERR_FEATURE_UNSUPPORTED; +} + +static int ssh_gss_deserialize_private(const char *, struct sshbuf *, + struct sshkey *) +{ + return SSH_ERR_FEATURE_UNSUPPORTED; +} + +static int ssh_gss_copy_public(const struct sshkey *, struct sshkey *) +{ + return SSH_ERR_FEATURE_UNSUPPORTED; +} + +static int ssh_gss_verify(const struct sshkey *, const u_char *, size_t, + const u_char *, size_t, const char *, u_int, + struct sshkey_sig_details **) +{ + return SSH_ERR_FEATURE_UNSUPPORTED; +} + +static const struct sshkey_impl_funcs sshkey_gss_funcs = { + /* .size = */ NULL, + /* .alloc = */ NULL, + /* .cleanup = */ NULL, + /* .equal = */ ssh_gss_equal, + /* .ssh_serialize_public = */ ssh_gss_serialize_public, + /* .ssh_deserialize_public = */ ssh_gss_deserialize_public, + /* .ssh_serialize_private = */ ssh_gss_serialize_private, + /* .ssh_deserialize_private = */ ssh_gss_deserialize_private, + /* .generate = */ NULL, + /* .copy_public = */ ssh_gss_copy_public, + /* .sign = */ NULL, + /* .verify = */ ssh_gss_verify, +}; + +/* The struct is intentionally dummy and has no gss calls */ +static const struct sshkey_impl sshkey_gss_kex_impl = { + /* .name = */ "null", + /* .shortname = */ "null", + /* .sigalg = */ NULL, + /* .type = */ KEY_NULL, + /* .nid = */ 0, + /* .cert = */ 0, + /* .sigonly = */ 0, + /* .keybits = */ 0, /* FIXME */ + /* .funcs = */ &sshkey_gss_funcs, +}; const struct sshkey_impl * const keyimpls[] = { &sshkey_ed25519_impl, @@ -154,6 +154,7 @@ static const struct keytype keytypes[] = { &sshkey_xmss_impl, &sshkey_xmss_cert_impl, #endif + &sshkey_gss_kex_impl, NULL }; @@ -255,7 +256,7 @@ sshkey_alg_list(int certs_only, int plain_only, int include_sigonly, char sep) for (i = 0; keyimpls[i] != NULL; i++) { impl = keyimpls[i]; - if (impl->name == NULL) + if (impl->name == NULL || impl->type == KEY_NULL) continue; if (!include_sigonly && impl->sigonly) continue; diff --git a/sshkey.h b/sshkey.h index 71a3fddc..37a43a67 100644 --- a/sshkey.h +++ b/sshkey.h @@ -69,6 +69,7 @@ enum sshkey_types { KEY_ECDSA_SK_CERT, KEY_ED25519_SK, KEY_ED25519_SK_CERT, + KEY_NULL, KEY_UNSPEC }; diff --git a/packet.h b/packet.h --- a/packet.h (revision 8241b9c0529228b4b86d88b1a6076fb9f97e4a99) +++ b/packet.h (date 1703172586447) @@ -124,6 +124,7 @@ int ssh_packet_send2(struct ssh *); int ssh_packet_read(struct ssh *); +int ssh_packet_read_expect(struct ssh *, u_int type); int ssh_packet_read_poll2(struct ssh *, u_char *, u_int32_t *seqnr_p); int ssh_packet_process_incoming(struct ssh *, const char *buf, u_int len); int ssh_packet_process_read(struct ssh *, int); diff --git a/packet.c b/packet.c --- a/packet.c (revision 8241b9c0529228b4b86d88b1a6076fb9f97e4a99) +++ b/packet.c (date 1703172586447) @@ -1425,6 +1416,29 @@ return type; } +/* + * Waits until a packet has been received, verifies that its type matches + * that given, and gives a fatal error and exits if there is a mismatch. + */ + +int +ssh_packet_read_expect(struct ssh *ssh, u_int expected_type) +{ + int r; + u_char type; + + if ((r = ssh_packet_read_seqnr(ssh, &type, NULL)) != 0) + return r; + if (type != expected_type) { + if ((r = sshpkt_disconnect(ssh, + "Protocol error: expected packet type %d, got %d", + expected_type, type)) != 0) + return r; + return SSH_ERR_PROTOCOL_ERROR; + } + return 0; +} + static int ssh_packet_read_poll2_mux(struct ssh *ssh, u_char *typep, u_int32_t *seqnr_p) {
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